M642 6 x 4 x 2" White Corrugated Mailers, Pack of 50. Corrugated Mailers are super strong yet lightweight to save on postage. Corrugated Mailers are manufactured from 200#/ECT-32-B, white corrugated. Perfect for shipping small, lightweight fragile items. Crush resistant mailers fold to provide double walls of protection on front and sides. No tape, glue or staples needed.