Barrier Bubble® lining retains air better than alternative cushioning materials. Polypropylene exterior is moisture, puncture and ripresistant. Coextruded seams are heat sealed and burst proof. Selfseal closure features a tamper indicator. Envelope Size: 7 1/4 x 8; Envelope/Mailer Type: Cushioned; Closure: SelfAdhesive; Trade Size: N/A.