These cello sleeves are so unique, even the mailman will do a double take! They are an uncommon alternative to the standard envelope and are USPS approved for sending a variety of mail. These sleeves have a secure self adhesive strip closure and are fashioned from acid-free sturdy translucent plastic. They are popularly used for delivering promotional or marketing materials, artwork, invitations, personal mail, greeting cards, and bulky items. From personal to professional mailings, these unique envelopes cater to all your needs in superior efficacy.Details:Available in multiple colors5.0625" x 7.1875"100 cello sleevesSelf adhesive closureBooklet opening with straight flapPlastic