Most decorative padded envelopes are constructed from polyethylene with an internal air-bubble (bubble) layer. Listings typically describe them as polyethylene or air-bubble polyethylene construction.
Many padded envelopes use self-adhesive (self-sealing) closures; some listings also show mailers without a closure.
Descriptions commonly specify internal bubble cushioning and often note 3/16" high-quality bubbles as the padding.
These mailers are described as suitable for small to semi-fragile items such as standard CDs/DVDs/video games, picture frames, paperback books, socks and gloves, delicate documents, and artwork.
Listings indicate that ink, stamps, and mailing labels adhere easily to these mailers. Some designs also provide a clear write-on area or panel where you can print or hand-write the recipient address and add postage.