Bubble Mailers offer strong, air bubble protection. Ideal for mailing pictures, cassettes, jewelry and more. Tough outer layer provides stiffness and rugged durability. Water-resistant design is lightweight for postage savings. No. 4 mailers feature a pressure-sensitive strip closure. Simply peel away liner and seal. Envelopes are preprinted with "To" and "From" address lines. Each contains a high percentage of recycled paper.