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Updated: 06 Apr 2026

10 Best Box Mailers 20-x-20

#1 Best Pick
100x Poly Mailer Courier Bags Self Sealing Packing Plastic Shipping Mailing Satchel Exterior Colour White Thickness 60 Micron Multiple Sizes (255 x 330mm)

100x Poly Mailer Courier Bags Self Sealing Packing Plastic Shipping Mailing Satchel Exterior Colour White Thickness 60 Micron Multiple Sizes (255 x 330mm)

Brand: Aznpac
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  • BAG DIMENSIONS AVAILABLE – 160x230mm., 190x260mm, 255x330mm, 310x405mm, 350x480mm, 430x545mm, 600x650mm
  • SELF SEALING – for Easy Packaging
  • PREMIUM QUALITY SATCHEL – 60 Micron Thickness
  • SUPER STRONG
  • Waterproof
  • Tear & Scratch Resistant
  • ALL PURPOSE MAILER – Shipping Parcels for your eCommerce Business
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#2 Best Value
Aviditi M20161 Jumbo Fold-Over Mailer, 20" Length x 16" Width x 1" Height, White (Bundle of 20)

Aviditi M20161 Jumbo Fold-Over Mailer, 20" Length x 16" Width x 1" Height, White (Bundle of 20)

Brand: BOX USA
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  • These one-piece Jumbo Fold Over Mailers are great for oversized flat items like portfolios, maps and blue prints.
  • Mailer fully opens for easy packing. Simply lay product on the flat mailer, fold in and seal with tape.
  • Attractive 200#/ECT-32-B white corrugated construction makes an impressive presentation.
  • Proudly made in the USA!
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#3 Budget Pick
EnDoc Tyvek Envelopes 10x15 –Strong Lightweight Professional Shipping Mailer Tear Resistant Tyvek Construction & Easy Self Seal Closure – Bright White Dupont – Bulk Pack of 15 – 10 x 15

EnDoc Tyvek Envelopes 10x15 –Strong Lightweight Professional Shipping Mailer Tear Resistant Tyvek Construction & Easy Self Seal Closure – Bright White Dupont – Bulk Pack of 15 – 10 x 15

Brand: EnDoc
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  • MUCH STRONGER THAN PAPER ENVELOPES - Classic White Mailers Are Perfect for Sending Documents, Invoices, Checks & Other Office Correspondence; Box of 20 Sheets
  • INDESTRUCTIBLE DUPONT DESIGN - Lightweight But Strong, Durable Tyvek Material Resists Ripping, Tearing, Punctures, Rain, Moisture & Other Common Postal Threats
  • CONVENIENT SELF SEAL CLOSURE - Peel Back the Sticker to Quickly & Effortlessly Seal & Send; Open End Catalog Orientation Enables Fast Paper & Packet Stuffing
  • SUPERIOR SHIPPING PROTECTION - Double Reinforced Construction, Opaque Color & Super Sticky Glue Offers Maximum Security for Confidential Business Mail
  • BUY CHECKOMATIC & SAVE BIG - Stock Up on Bulk Supplies & Enjoy the Best Prices in the Industry; Lighter Weight Saves On Postage Half The Weight Of Paper Envelopes; Envelope Packs Available in 6x9, 9x12, 10x13, 10x15 & 12 x 15 1/5
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#4 Top Choice
Mead #6-3/4 Envelopes, Security Printed Lining for Privacy, Gummed Closure, 3-5/8" x 6-1/2", All-Purpose 20-lb Paper, White, 80 per Box (75212)

Mead #6-3/4 Envelopes, Security Printed Lining for Privacy, Gummed Closure, 3-5/8" x 6-1/2", All-Purpose 20-lb Paper, White, 80 per Box (75212)

Brand: Mead
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  • White envelopes with security lining ensure privacy
  • 6-3/4 size envelopes measure 3-5/8" x 6-1/2"
  • 80 envelopes per box. Customizable: No
  • 20 lb. paper.
  • Made in United States
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#5 Popular Choice
100PCS Mailing Box 310 x 230 x 105mm A4 BX2 B2 Die Cut Mailer Shipping Packing Corrugated Box

100PCS Mailing Box 310 x 230 x 105mm A4 BX2 B2 Die Cut Mailer Shipping Packing Corrugated Box

Brand: ExtraPrint
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  • Premium quality.
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#6 Top Pick
100PCS Mailing Box 220 x 160 x 77mm A5 BX1 B1 Die Cut Mailer

100PCS Mailing Box 220 x 160 x 77mm A5 BX1 B1 Die Cut Mailer

Brand: ExtraPrint
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  • Premium quality.
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#7 Top Pick
Corrugated Cardboard Shipping Boxes, 100x100x20mm (4"x4"x0.8") Small Parcel Boxes, Packaging Mailing Boxes for Business, Posting, Large Letter Packet Shipping, Storing or Gift(Pack of 25)

Corrugated Cardboard Shipping Boxes, 100x100x20mm (4"x4"x0.8") Small Parcel Boxes, Packaging Mailing Boxes for Business, Posting, Large Letter Packet Shipping, Storing or Gift(Pack of 25)

Brand: PACK4YA
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  • Made from strong 32ECT-E single wall corrugated kraft cardboard which is Eco-friendly, recyclable and sturdy for daily use
  • Outer size: 100mm x 100mm x 20mm, inner size when made up: 90mm x 97mm x 17mm. Item weight is 18g per box
  • Pack, Ship, Mail, or Store small items in these cartons, they make the perfect box for those little products or gifts that need to be sent out or stored until ready to use
  • Package ships flat packed for easy storage, and are easy to assemble in seconds – no tapes, glue or staplers are needed
  • 100% SATISFACTION: Please contact us via e-mail for any case, we guarantee our customers 100% money back in 90 days.
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#8 Top Pick
50Pcs Bubble Mailers Padded Envelopes Lined Poly Mailer Self Seal Pink 15x20cm

50Pcs Bubble Mailers Padded Envelopes Lined Poly Mailer Self Seal Pink 15x20cm

Brand: BIGTEDDY
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  • Size:11x15cm/ 15x20cm/ 25x30cm
  • Material: PE
  • Features:Adhesive, Water Resistent, Tear Resistent, Padded
  • Plastic varieties: PO, PE
  • Sealing length: 4cm
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#9 Top Pick
Super-Flat Die Cut Mailing Box 180 x 100 x 16mm Cardboard Mailer (Pack of 20)

Super-Flat Die Cut Mailing Box 180 x 100 x 16mm Cardboard Mailer (Pack of 20)

Brand: Generic
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  • Box Width ~ 180mm
  • Box Length ~ 100mm
  • Box Height ~ 16mm (Thickness)
  • Suitable for a mailbox delivery, Stamp OK
  • Lightweight Design, 100% Recyclable
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#10 Top Pick
Super-Flat A3 Mailing Box 440 x 320 x 20mm Cardboard Mailer, Rigid Self-Locking Flat Mailer for Documents & Prints (Pack of 10)

Super-Flat A3 Mailing Box 440 x 320 x 20mm Cardboard Mailer, Rigid Self-Locking Flat Mailer for Documents & Prints (Pack of 10)

Brand: Generic
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  • Perfect for A3 Documents & Prints – Measures 440 x 320 x 20mm, ideal for sending flat artwork, certificates, posters, and other important documents safely.
  • Super-Flat & Efficient Design – Slim profile keeps contents secure and professional without extra bulk.
  • Rigid Cardboard – Strong, durable construction ensures your items arrive undamaged and pristine.
  • Self-Locking Die-Cut Style – Easy-to-use folding design keeps documents safe without tape or extra packaging.
  • Eco-Friendly & Practical – Plain white exterior with brown interior; optimized sizing reduces waste and minimizes your carbon footprint.
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