Water-, puncture-, tamper- & tear-resistant poly construction ensures top-notch protection for your important materials & merchandise. High-strength heat-welded seams & an overall tensile strength of 4.5 lb / in, with a minimum 300% elongation before breakage, keeps your contents secure, even when the mailer is overstuffed. Self-adhesive, tamper-evident closure & an easy-open tear-strip help you streamline packing tasks on your end while simplifying getting to the goods on your customer's end. Contrasting silver-gray interior color delivers excellent opacity to make sure confidential materials remain so. Exterior accepts all common adhesive & ink types. Seam Type: Weld; Flap Type: Square; Security Tinted: No; Opening: Open End.