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Conformer Envelopes, Rigid Expansion Mailers, 25 Count

  • Protect your mailings throughout transit with our heavy-duty rigid conformer mailers made from sturdy 14 pt white paperboard that resists bending or folding and keeps your documents and booklets secure.
  • Mail documents of varying thickness or even stacks of documents all in the same envelope thanks to the score lines on all four sides of the mailer. These allow the envelope to expand uniformly and fit around your contents snugly.
  • These large, extra durable conformer envelopes measure 9.75 x 12.25 inches. Each glue seam is inset from the edges to increase the strength of the mailer and keep your contents safe.
  • Ship everything from thin documents and booklets to thick stacks of papers or even books up to 5/8” thick. The corners of these conformer mailers are uniquely constructed so they expand seamlessly at the bottom corners by up to 0.625 inches.
  • Our 25 pack of conformer envelopes stores flat and replaces the need for expensive gusseted envelopes, Tyvek mailers, padded or bubble mailers, and boxes that take up room in your supply closet. 


Conformer envelopes expand uniformly to fit whatever you slide inside. Shipping documents, booklets, or even books is easier than ever. These mailers measure 9.75” x 12.25” and were designed with flexibility and versatility in mind, since they fit all manner of mailings and store flat for easy, space-saving storage.

Patented construction incorporates 14 pt paperboard, inset glue seams, and uniquely engineered expanding corners to provide extra durable strength. Our mailers expand along pre-scored lines to fit an extra 5/8” worth of thickness – but only when you need it. This eliminates the need for fillings like bubble wrap or packing peanuts. And the contents within your mailers will stay flat, secure, and safe throughout transit thanks to the heavy-duty peel-and-seal flap which provides a permanent seal without the need for extra packing tape.

We stand behind our products completely. We understand that buying products online can sometimes be difficult because you cannot physically see what you are buying; however, if our product is not exactly what you are looking for or does not meet your expectations, then we welcome you to send them back anytime for a 100% refund. Click here for more information regarding refunds or returns >

Key Features:

  • 9 3/4 x 12 ¼-inch mailers with 5/8-inch expansion
  • Conformer mailers
  • Self-seal closure
  • E-Z open tear string
  • White 14pt paperboard
  • Package quantity: 25

Product Details:

  • Brand: Blue Summit Supplies
  • Part #: BSS-92588-037
  • SKU: BSS-92588-037
  • Barcode: X002CHFKTB
  • Package dimensions: 12.3 x 9.8 x 2 in
  • Package weight: 1.5 lb