PJ4 Opaque Poly Mailers measure 255mm x 340mm making them a versatile size to use in posting many non-fragile items. Made in professional looking extra strength 75 micron white polythene, these mail bags are extremely robust and resistant to water, punctures and tearing. Poly mailers are compact to store and easy to pack with a ready to use self-adhesive closure strip that forms a tamper-proof seal to keep goods safe and secure. Because they are so light (each PJ4 sized mailer weighs just 9g) Poly Mailers keep postage costs down while still offering reliable protection for goods in transit.