Poly Envelopes feature roomy pockets and a flap with elastic cord and button closure to keep documents secure inside. Full-length, open-top pocket on back keeps supporting material at hand. Two-tone translucent polypropylene construction allows instant identification of contents inside the letter-size envelope.Poly Envelopes feature roomy pockets and a flap with elastic cord and button closure to keep documents secure inside. Full-length, open-top pocket on back keeps supporting material at hand. Two-tone translucent polypropylene construction allows instant identification of contents inside the letter-size envelope.