20" x 24" x 4" Expansion Poly Mailers. Strong polyethylene mailers protect products from moisture during shipping. Features a gusseted bottom to allow for thicker items such as binders, books and catalogs. Puncture, moisture, tamper and tear resistant. High strength seams will keep contents intact even if over packed. The outer surface of the mailer is white and the inner lining is silver. Labels, ink and stamps adhere well. Opens easily with a perforated tear strip.