These self adhesive card board #10 envelope mailers provide an easy and convenient was to ship your coins. Each mailer measures 7 3/4x8 5/8 inches and folds in half to fit comfortably within a standard #10 mailing envelope. The board is made of a cushioned fluted corrugated acts as a pillow for the contents. According to the manufacturer the sturdy adhesive is strong enough to keep the mailer closed, but can be reopened if needed. You ever try to reuse one of these? They are indispensable for mailing coin, stamp and trading cards sold on eBay under $20 and for protecting valuable merchandise in padded envelopes. Sold in 10 or 20 packs.