Poly bubble mailers are lined inside with bubble cushion and are resistant to tearing, tampering, puncturing, and moisture. They’re ideal for shipping items that need more protection, such as electronics, jewelry, books, handmade goods, makeup containers, books, and more. Flat poly mailers are unlined inside and are resistant to tearing, tampering, puncturing, and moisture, too. They’re ideal for shipping items that need less protection, including clothing, boxed jewelry and candy, soft handmade goods, shoe boxes, and more. All custom mailers feature a peel-and-seal adhesive strip on the flap.