Aviditi M543K Corrugated Mailers, 5" x 4" x 3", Kraft (Pack of 50) Kraft Corrugated Mailers are light-weight to save on postage Crush resistant mailer folds to provide double walls of protection on front and sides Kraft Corrugated Mailers are manufactured from 200#/ECT-32-B Kraft corrugated Mailers fold together in seconds - no tape or glue needed