Sealed Air 49678 TuffGard Self-Seal Cushioned Mailer, #000, 4 x 8, White (Case of 25) White polypropylene shipping mailer features a self-seal closure and a Barrier Bubble air cellular lining. Puncture-, tamper-, and water-resistant. Heat-seal seams. Lightweight Barrier Bubble air cellular lining. White polypropylene shipping mailer features a self-seal closure and a Barrier Bubble air cellular lining.