The Packaging Wholesalers 4 x 4 x 3 Inches Corrugated Mailer, 50-Count (BSM443) Perfect for shipping small, lightweight, fragile items. Each corrugated mailer is manufactured from 32ect-B oyster white corrugated. Crush resistant mailers fold to provide double walls of protection on front and sides. Our unique wave rule edge virtually eliminates paper cuts. These one piece mailers fold together in seconds.