Most waterproof padded envelopes are made from polyethylene (a durable plastic). Listings typically describe the material as strong polyethylene or simply as plastic.
Most use a self-adhesive, self-sealing strip (peel-and-seal). Listings commonly describe these closures as tamper-evident or tamper-resistant for quick, secure packing.
Terminology varies across listings. Some use stronger wording like "WATERPROOF/DUST PROOF," others say "WATER RESISTANT," and some call the material "MOISTURE-RESISTANT." The exact phrase differs by product.
They include an internal plastic bubble cushioning layer. Listings often note bubble quality (for example, "3/16" high quality bubbles") to indicate the level of padding.
Some listings note recycled content and recyclability—for example, one set mentions 50% recycled content and that the bags are store drop-off recyclable.