Redi-Strip Poly Expansion Mailer, #4 1/2, Square Flap, Redi-Strip Adhesive Closure, 11 x 13, White, 100/CartonExcellent for shipping large orders, Qwith an expansion to accommodate overstuffing. It's good practice to keep a stock on hand, in the event that one is needed. Between the open end design and self sealing closure, flexible poly mailers streamline the process to get deliveries out on time.