50 Companies That Use Stamps.com [2024]

Updated: May 21st, 2022

Buy USPS postage online from your PC, easily print postage stamps and shipping labels for all USPS mail classes.

We put together a list of the biggest companies that use Stamps.com, along with some Stamps.com testimonials and Stamps.com case studies.

Here's the list:

1. Presidio Natural Pet Co

Presidio Natural Pet Co is a cat treats brand started by Spyq Sklar in 2015. Presidio Natural Pet Co uses Stamps.com for their business.

Revenue
$30K / month
Team
2 founders / 3 employees
Location
Quebec City, Quebec, Canada

article

How I Built A Successful Company Selling Cat Treats Online

Cat Sushi went from repackaging tuna flakes to creating a unique pet treat brand by leveraging their connections to the pet industry and focusing on a beautiful design that set them apart from their competition.

Read by 13,099 founders

2. Robo 3D

Robo 3D is a 3D Printing Business started by Braydon Moreno in 2017. Robo 3D uses Stamps.com for their business.

Revenue
$150K / month
Team
2 founders / 30 employees
Location
San Diego, California, USA

article

Raising 13x Their Original Kickstarter Goal With a Viral 3D Printer

Robo 3D, a company that designs 3D printers for consumers, launched their first product on Kickstarter which raised $650,000 in just 35 days, and now has sold their products in over 4,505 cities across 101 countries worldwide.

Read by 10,372 founders

3. Headline Solar

Headline Solar is a candle business started by Kevin Gillespie in 2019. Headline Solar uses Stamps.com for their business.

Revenue
$500K / month
Team
2 founders / 20 employees
Location
Schaumburg, Illinois, USA

article

Selling Over 4,500 Candles

Wax & Wick is a 100% soy candle company with wood wicks, that creates environmentally-friendly products; starting off making $1,000 a month in 2015, they brought in about $20,000 per month during Q3 2017 and plan to add ten new scents and a premium sized jar for 2018's $50,000 per month goal.

Read by 19,361 founders

4. TomboyX

TomboyX is a men's underwear brand started by Fran Dunaway in 2013. TomboyX uses Stamps.com for their business.

Revenue
$2M / month
Team
2 founders / 34 employees
Location
Seattle, Washington, USA

article

How A Gender Neutral Garment Became A $500K/Month Business

TomboyX, a gender-neutral clothing company, has consistently increased its revenue over 100% each year and expanded from zero employees to 15 in just two years by focusing on quality underwear and listening to customer feedback.

Read by 11,473 founders

5. Dick At Your Door

Dick At Your Door is a dessert boxes store started by Adam Hascall in 2015. Dick At Your Door uses Stamps.com for their business.

Revenue
$125K / month
Team
1 founders / 3 employees
Location
California, USA

article

I Make $1.5M/Year Shipping Chocolate Penises To Your Friends

Dick At Your Door is an e-commerce shop that grew almost 10x within the last eight months by selling anonymous pranks such as 5 oz chocolate penises, and its founder shares his journey that started as a joke to becoming a professional chocolatier.

Read by 16,660 founders

6. Starter Story

Starter Story is a niche blog started by Pat Walls in 2017. Starter Story uses Stamps.com for their business.

Revenue
$250K / month
Team
1 founders / 6 employees
Location
New York, New York, USA

article

How I Turned A Crappy Idea Into A $3M/Year Business

Starter Story grew to 1.4 million monthly visitors and millions in annual revenue by sharing the stories of entrepreneurs. Pat breaks down the early days and how he grew the business into something that changed his life.

Read by 78,046 founders

7. Lazyjack Press

Lazyjack Press is a preppy clothing business started by Miriam Zelinsky in 2012. Lazyjack Press uses Stamps.com for their business.

Revenue
$21K / month
Team
1 founders / 0 employees
Location
New York, New York, USA

article

I Started A Preppy Clothing Brand That Makes $21K/Month

Lazyjack Press, a luxury men's accessories brand, offers high-quality, Italian silk ties, pocket squares, bow ties, and socks with uniquely named designs and a focus on fun, appealing to audiences of all ages, and is primarily sold through trade shows and pop-up shops.

Read by 20,386 founders

8. Encircled

Encircled is a women's clothing line started by Kristi Soomer in 2012. Encircled uses Stamps.com for their business.

Revenue
$200K / month
Team
1 founders / 10 employees
Location
Toronto, Ontario, Canada

article

Embracing A Minimalist Wardrobe And Building A Business Around It

Encircled is a sustainable fashion brand that has achieved over 300% growth in the past two years through a direct-to-consumer eCommerce model and a focus on versatile, responsibly-made, and timeless designs, with a marketing strategy that emphasizes content and email.

Read by 5,933 founders

9. Kitchen Safe

Kitchen Safe is a tupperware business started by David Krippendorf in 2012. Kitchen Safe uses Stamps.com for their business.

Revenue
$150K / month
Team
3 founders / 18 employees
Location
Southlake, Texas, USA

article

Transforming One Idea Into A $150K/Month Business

The founder of Kitchen Safe, David Krippendorf, invented the world's first time-lock container that has helped customers avoid snacking on junk food along with other temptations, with over half of the users also using it for other non-food related items such as cell phones, cigarettes, and credit cards.

Read by 10,669 founders

10. Tortuga

Tortuga is a backpack line started by Fred Perrotta in 2010. Tortuga uses Stamps.com for their business.

Revenue
$300K / month
Team
2 founders / 9 employees
Location
Remote

article

How We Started A $300K/Month Business Selling Carry On Travel Backpacks

How Tortuga bootstrapped their way to seven figures in revenue, by solving a problem for travelers with their carry-on sized travel backpacks, after overcoming challenges in design, manufacturing, and advertising.

Read by 12,978 founders

11. KPOP Foods

KPOP Foods is a hot sauce business started by Theo Lee in 2017. KPOP Foods uses Stamps.com for their business.

Revenue
$200K / month
Team
2 founders / 5 employees
Location
Los Angeles, California, USA

article

How Two Students Made $100K Bringing Korean Hot Sauce To America

KPOP Foods, a Korean food company, generated nearly $100,000 in revenue since last year through its successful Kickstarter campaign and Amazon's Choice badge; they have entered over 90 specialty stores throughout the west coast and are currently raising an investment round to expand their distribution into major retailers and are launching new sauces later this year.

Read by 10,503 founders

12. Beach Gladiator

Beach Gladiator is a skin care product line started by Michael Vahey in 2015. Beach Gladiator uses Stamps.com for their business.

Revenue
$8.5K / month
Team
2 founders / 4 employees
Location
Virginia, USA

article

These Two Founders Created A Successful Product For Their Kids

Beach Gladiator, a chafing solution intended for the beachgoers and beach market, went from a small regional business to a national brand through grass root types of effort like word of mouth communication and event participation.

Read by 5,229 founders

13. Breathe Healthy

Breathe Healthy is a respirator mask business started by Michael Vahey in 2009. Breathe Healthy uses Stamps.com for their business.

Revenue
$90K / month
Team
1 founders / 3 employees
Location
Virginia, USA

article

Starting A $90K/Month Respirator Mask Business

Breathe Healthy, a wearable respiratory protection business, has surpassed 1 million in sales as of 2017, continues to grow, and has disrupted the "traditional" paper/disposable mask market with a unique, comfortable product, achieving 80% gross margin by focusing on small markets and onboarding with online retail partners.

Read by 10,169 founders

14. Pain Care Labs a dba of MMJ Labs

Pain Care Labs a dba of MMJ Labs is a medical device company started by Amy Baxter MD in 2006. Pain Care Labs a dba of MMJ Labs uses Stamps.com for their business.

Revenue
$208K / month
Team
1 founders / 7 employees
Location
Atlanta, Georgia, USA

article

How A Doctor Got On Shark Tank And Saved 31M People From Pain

Pain Care Labs, founded by a pediatric emergency doctor after inventing a vibrating ice pack bee, Buzzy, has sold over 31 million units while focusing on non-pharmaceutical pain relief, and recently launched a crowdfunding campaign for their latest product, DuoTherm.

Read by 26,017 founders

15. Boutique Rye

Boutique Rye is a boutique started by Gia Paddock in 2017. Boutique Rye uses Stamps.com for their business.

Revenue
$10K / month
Team
2 founders / 0 employees
Location
Phoenix, Arizona, USA

article

How I Grew My Clothing Boutique to $10K/Month in 6 Months

Boutique Rye is an online-only women's clothing and accessories boutique that has grown to 3,200 Facebook Group members and a successful website through organic customer sharing, live sales, and open communication with customers.

Read by 36,945 founders

16. SmartyPits

SmartyPits is a deodorant brand started by Stacia Guzzo in 2014. SmartyPits uses Stamps.com for their business.

Revenue
$183K / month
Team
2 founders / 13 employees
Location
Bend, OR, USA

article

How Stacia Guzzo Pivoted and Started A $58K/Month Deodorant Product

SmartyPits is a fast-growing deodorant company that has gone from making under $100,000 in 2016 to making over $500,000 by Q3 2018, after the founder's experience as a breast cancer survivor led to developing an aluminum-free deodorant.

Read by 14,366 founders

17. Outlaw

Outlaw is a soap business started by Danielle Vincent in 2013. Outlaw uses Stamps.com for their business.

Revenue
$380K / month
Team
2 founders / 13 employees
Location
Sparks, NV, USA

article

Leaving The Cubicle To Start A $23K/Month Soap Company

Outlaw Soaps, a soap company that started with just $13.72 of supplies, now makes an average of $23,000/month, with 46% of website orders from repeat customers who are loyal to the company's unique products and top-notch customer service.

Read by 25,243 founders

18. Upcart

Upcart is a dolly product started by Michael Reznik in 2015. Upcart uses Stamps.com for their business.

Revenue
$583K / month
Team
2 founders / 4 employees
Location
Columbus, Ohio, USA

article

How Two Unlikely Partners Invented the UpCart and Went Viral on QVC

UpCart LLC, the company behind the patented line of all-terrain folding carts and hand trucks, has seen tremendous growth over the past few years, with sales increasing from $3.2M in 2016 to a projected $7M in 2018, thanks in part to its QVC Sprouts live-sell success and viral Facebook marketing efforts.

Read by 10,494 founders

19. Ashland Leather

Ashland Leather is a wallet brand started by Phil Kalas in 2011. Ashland Leather uses Stamps.com for their business.

Revenue
$60K / month
Team
2 founders / 8 employees
Location
Chicago, Illinois, USA

article

Growing A Handcrafted Leather Goods Business To $600K/Year

A successful handcrafted leather goods business that started with just $1000, has grown to $600k annual sales, thanks to a strong brand philosophy, a focus on specific niche terms for SEO, personalized customer experiences, and a team that is trusted to achieve goals autonomously.

Read by 6,661 founders

20. Compelling Science Press

Compelling Science Press is a niche blog started by Joe Stech in 2016. Compelling Science Press uses Stamps.com for their business.

Team
1 founders / 0 employees
Location
Louisville, CO, USA

article

Turning A Science Fiction Hobby Into A Successful Side Project

A software manager has found success with Compelling Science Fiction, which publishes short stories twice a year, paying authors 6 cents per word with the funds raised from his 1,600 readers on Patreon; revenue from ads and Google and Facebook ads was too high and Kickstarter campaigns have been more successful.

Read by 5,435 founders

21. Bang-Up Betty

Bang-Up Betty is a jewelry making business started by Stacey Bowers in 2013. Bang-Up Betty uses Stamps.com for their business.

Revenue
$7K / month
Team
1 founders / 1 employees
Location
North Little Rock, Arkansas, USA

article

Growing A Handmade Jewelry Hobby Into A Successful Business

How Stacey turned her handmade jewelry hobby into a business that generates an average revenue of $6,000 per month, with a focus on staying true to your designs and customers, and the importance of organic marketing through social media and SEO.

Read by 11,526 founders

22. Comfy Cup LLC

Comfy Cup LLC is an outdoor sports store started by Kyler Russell in 2016. Comfy Cup LLC uses Stamps.com for their business.

Revenue
$25K / month
Team
2 founders / 2 employees
Location
Midwest, Kansas, USA

article

How A 12 Year Old Started A $100K Athletic Cup Product

A 12-year-old invented The Comfy Cup, a more comfortable athletic cup for boys, which has grown into a successful business venture grossing over $100k in revenue last year, available on Amazon, The Grommet, and in local sporting goods stores.

Read by 7,393 founders

23. Oh My Balm

Oh My Balm is a skin care product line started by Meredith Moseley-Bennett & Yolanda Grbic in 2017. Oh My Balm uses Stamps.com for their business.

Revenue
$2K / month
Team
2 founders / 0 employees
Location
Glen Ridge, New Jersey, USA

article

How Two Moms Started A Business Selling Homemade Body Butter

Two moms start a side hustle selling all-natural body products, doubling sales since their launch in 2017 with over 75 craft shows, promoting a non-profit source for their shea butter and self-promotion through podcasts, lining up retail interest from exposure.

Read by 34,852 founders

24. Sarah Paints Pets

Sarah Paints Pets is an art business started by Sarah Miller in 2018. Sarah Paints Pets uses Stamps.com for their business.

Revenue
$3.5K / month
Team
1 founders / 1 employees
Location
Atlanta, Georgia, USA

article

Sarah Miller Started A Business Selling Her Own Artwork Online

Sarah Miller started a small business, sarahpaintspets, where she creates custom watercolor pet portraits for animal lovers across the US and Canada, which has lead to an average income per painting of $150 and receives word-of-mouth referrals as the biggest source of income.

Read by 8,361 founders

25. The Christmas Tree Hugger

The Christmas Tree Hugger is a christmas tree accessory business started by Ryan Kenny in 2017. The Christmas Tree Hugger uses Stamps.com for their business.

Revenue
$35K / month
Team
1 founders / 2 employees
Location
Atlanta, Georgia, USA

article

How Ryan Kenny Started The Christmas Tree Hugger

The Christmas Tree Hugger has quickly become a 5-star rated holiday product, generating an average of $35k a month with a successful Kickstarter campaign and appearances on QVC & Shark Tank.

Read by 7,897 founders

26. The Cut Buddy

The Cut Buddy is a men's grooming company started by Joshua Esnard in 2015. The Cut Buddy uses Stamps.com for their business.

Team
2 founders / 4 employees
Location
Chapel Hill, North Carolina, USA

article

27. GloveStix

GloveStix is a cleaning products business started by Krista Woods in 2014. GloveStix uses Stamps.com for their business.

Revenue
$60K / month
Team
1 founders / 1 employees
Location
Ashburn, Virginia, USA

article

28. Brazyn Life

Brazyn Life is a foam roller business started by Nate Lawrie in 2015. Brazyn Life uses Stamps.com for their business.

Team
1 founders / 4 employees
Location
Santa Barbara, California, USA

article

29. Woodies

Woodies is a sunglasses business started by Cory Stout in 2012. Woodies uses Stamps.com for their business.

Revenue
$190K / month
Team
1 founders / 1 employees
Location
Santa Monica, CA, USA

article

Woodies Sunglasses: $3.5 Million Per Year With One Employee

Woodies, a wood sunglasses brand founded by Cory Stout, reached over $3.5M in revenue in 2018, despite starting with only $15K from a failed business and has succeeded through Amazon sales, spending $50K monthly on PPC and keeping ACOS at 30%.

Read by 22,857 founders

30. Emu Joy

Emu Joy is a skin care product line started by Carole Rains in 2014. Emu Joy uses Stamps.com for their business.

Revenue
$33K / month
Team
1 founders / 1 employees
Location
New Jersey, USA

article

Starting A Successful Business Selling Emu Oil Creams

Emu Joy is a profitable business that has sold over 50,000 bottles, jars, and tubes of all-natural emu oil products online, with more than 90% of sales on Amazon, and founder Carole Rains shares tips on success from bootstrapping and branding, to using multiple checking accounts, and fostering relationships.

Read by 7,368 founders

31. AmmoniaSport LLC

AmmoniaSport LLC is a skin care product line started by Justin Rapoport in 2017. AmmoniaSport LLC uses Stamps.com for their business.

Revenue
$80K / month
Team
1 founders / 0 employees
Location
San Diego, California, USA

article

32. Everest Horology Products

Everest Horology Products is a watch accessories business started by Michael DiMartini in 2012. Everest Horology Products uses Stamps.com for their business.

Team
2 founders / 8 employees
Location
Saint Louis, Missouri, USA

article

33. ZBiotics

ZBiotics is a beverage company started by Zack Abbott in 2016. ZBiotics uses Stamps.com for their business.

Team
2 founders / 6 employees
Location
San Francisco, California, USA

article

34. Firehouse Moustache Wax, LLC

Firehouse Moustache Wax, LLC is started by John Pitts in 2006. Firehouse Moustache Wax, LLC uses Stamps.com for their business.

Team
2 founders / 0 employees
Location
Floure, Occitania, France

article

35. Brine Brothers

Brine Brothers is a hangover cure product started by Harris Derner in 2017. Brine Brothers uses Stamps.com for their business.

Revenue
$10K / month
Team
2 founders / 0 employees
Location
New York, New York, USA

article

How We Launched A Viral Pickle Juice To Cure Our Hangovers

Brine Brothers sells all-natural pickle brine (pickle juice), generating over $10,000/month and winning an investment from Barstool and Jon Taffer, and is determined to become a million-dollar beverage company.

Read by 15,932 founders

36. Matador

Matador is a travel products business started by Chris Clearman in 2014. Matador uses Stamps.com for their business.

Team
1 founders / 0 employees
Location
Boulder, Colorado, USA

article

37. Boosa Tech

Boosa Tech is a portable phone chargers business started by Chris Reimer in 2017. Boosa Tech uses Stamps.com for their business.

Revenue
$4K / month
Team
1 founders / 1 employees
Location
Saint Louis, Missouri, USA

article

How I'm Building A Side Hustle With An Unorthodox Business Mindset

Boosa Tech's founder, Chris Reimer, built a side hustle selling portable phone chargers and successfully launched his business through Amazon FBA and later Shopify, averaging $2,000/month in sales.

Read by 7,542 founders

38. Life and Limb Printing

Life and Limb Printing is a screen printing business started by Adam Tanaka in 2010. Life and Limb Printing uses Stamps.com for their business.

Revenue
$80K / month
Team
1 founders / 3 employees
Location
Nashville, Tennessee, USA

article

From Scrubbing Floors To Running A $1M Screen Printing Business

This case study features an entrepreneur who started a screen printing company with no financing or investors, and despite struggling for the first few years, was able to grow his business to hit $80,000 in revenue in October 2018 and is set to hit $1 million by the end of 2019.

Read by 16,957 founders

39. Scrubblade Inc.

Scrubblade Inc. is an aftermarket car parts business started by Billy Westbrook in 2007. Scrubblade Inc. uses Stamps.com for their business.

Revenue
$325K / month
Team
1 founders / 6 employees
Location
Temecula, California, USA

article

How I Invented A Better Windshield Wiper And A $2M/Year Business

Scrubbleblade is a windshield wiper company that sells #1 in the H.D. trucking industry and was awarded wiper blade of the year by Frost & Sullivan in 2018; they focus on a specific target customer while offering subscriptions and utilizing social media.

Read by 15,495 founders

40. TAB Performance

TAB Performance is a motorcycle parts business started by Justin Pflanz in 2004. TAB Performance uses Stamps.com for their business.

Revenue
$600K / month
Team
2 founders / 9 employees
Location
Lincoln, Nebraska, USA

article

How Two Brothers Started A $4.8M/Year Motorcycle Parts Manufacturer

TAB Performance doubles annual sales with introduction of Zombie baffle, from manufacturing Harley-Davidson motorcycle exhausts, with founders attributing growth to constant evolution and listening to customers.

Read by 12,668 founders

41. CODDI

CODDI is a shoe brand started by Matthew Walters in 2019. CODDI uses Stamps.com for their business.

Revenue
$2K / month
Team
1 founders / 1 employees
Location
Chicago, Illinois, USA

article

How I Started A Boot Brand And Raised $61K With No Paid Advertising

CODDI, a boot company based in Chicago, raised just over $61k on Kickstarter and made $2.5k in sales in June, $2k in sales in July, and another $2k in August, all while utilizing free marketing methods like Instagram and Facebook posts to build a community before their website launch.

Read by 9,571 founders

42. Conundrum Publishing

Conundrum Publishing is an author started by Nick Thacker in 2017. Conundrum Publishing uses Stamps.com for their business.

Revenue
$20K / month
Team
1 founders / 2 employees
Location
Colorado, USA

article

How I Generate $10K/Month As An Indie Writer

This case study follows full-time thriller and action-adventure author Nick Thacker who earns between $10k to $20k per month from writing, predominantly through Amazon Kindle Unlimited sales, and goes in-depth into his self-publishing strategy which maximizes sales and minimizes costs, such as developing a mailing list and utilizing print-on-demand services.

Read by 10,808 founders

43. Payment for Stripe

Payment for Stripe is a payment app started by Ryan Scherf in 2015. Payment for Stripe uses Stamps.com for their business.

Revenue
$60K / month
Team
1 founders / 1 employees
Location
Minneapolis, Minnesota, USA

article

How I Created A $60K/Month App That Collects In-Person Payments Through Stripe

Payment.co, an app built on top of the Stripe payment gateway for creating card-present charges, has grown to process over $70M in volume annually since launching in 2015, with the app collecting a 1% service fee on every single charge.

Read by 23,496 founders

44. No Cold Feet LLC

No Cold Feet LLC is a socks business started by Mari & Matt McNamara in 2016. No Cold Feet LLC uses Stamps.com for their business.

Revenue
$20K / month
Team
2 founders / 0 employees
Location
Chicago, Illinois, USA

article

How We Started A $18K/Month Fun And Colorful Groomsmen Socks Company

No Cold Feet is a gifting company founded by Mari and Matt McNamara that focuses on fun and colorful sock designs for groomsmen gifts and has cumulatively sold over 10k orders in the last three years, passing $200k in revenue last year.

Read by 10,700 founders

45. TechKeys

TechKeys is a computer accessory business started by Brad Agdern in 2012. TechKeys uses Stamps.com for their business.

Revenue
$5K / month
Team
1 founders / 1 employees
Location
Chicago, Illinois, USA

article

How I Started A $5K/Month Side Hustle Selling Mechanical Keyboard Accessories

TechKeys, an online retail store dedicated to mechanical keyboard parts and accessories, grew from a hobby to a niche business earning $5,000 a month in revenue by leveraging the buying power of the group buy to manufacture additional inventory and offering them to buyers at a standard retail markup.

Read by 40,189 founders

46. Parker Baby Co.

Parker Baby Co. is a children's clothing business started by Kirsten and Sam in 2015. Parker Baby Co. uses Stamps.com for their business.

Revenue
$500K / month
Team
2 founders / 2 employees
Location
Colorado, USA

article

How We Started A $325K/Month Practical Baby Products Brand

Husband and wife team from Colorado started Parker Baby Co. in 2015, specializing in practical baby products that experienced rapid sales growth of 300%, 87%, and 48% in 2017-2019 and is expecting more than 65% growth in 2020, with $325k monthly earnings.

Read by 12,359 founders

47. Meowijuana

Meowijuana is a catnip products started by Chris Glissman in 2015. Meowijuana uses Stamps.com for their business.

Revenue
$200K / month
Team
1 founders / 11 employees
Location
Lenexa, Kansas, USA

article

How I Started A $200K/Month Catnip, Cat Toys And Treats Brand

Meowijuana, a catnip company founded in a one-car garage, has now become an emerging global brand with $200K in monthly revenue, selling catnip products in thousands of pet retailers worldwide, with 90% of sales coming from brick and mortar stores and national retail chains.

Read by 14,824 founders

48. Stonemaier Games

Stonemaier Games is a game development started by Jamey Stegmaier in 2012. Stonemaier Games uses Stamps.com for their business.

Revenue
$1.73M / month
Team
2 founders / 4 employees

article

How I Started A $40M-Revenue Business Creating Tabletop Games

How one founder turned a successful Kickstarter campaign into a $40 million tabletop game company with a focus on crafting a few special products each year and using social media to build community and relationships with customers.

Read by 13,307 founders

49. AwardWallet, LLC

AwardWallet, LLC is a travel rewards app started by Alexi Vereschaga in 2004. AwardWallet, LLC uses Stamps.com for their business.

Revenue
$150K / month
Team
2 founders / 29 employees
Location
Bethlehem, Judea and Samaria, Palestinian Territory

article

How I Launched A $150K/Month Frequent Flyer Programs Tracking App

AwardWallet is a loyalty program tracking website which has grown to over $150,000 in monthly revenue, and since launch has retained users mainly through word of mouth due to its superior product in the space.

Read by 10,305 founders

50. Apeloig Collection

Apeloig Collection is a modern design aesthetic products started by Daniela V Apeloig in 2015. Apeloig Collection uses Stamps.com for their business.

Team
2 founders / 4 employees

article

meet the author
Pat Walls