https://www.officemonster.co.uk/high-security-envelopes/tyvek-pocket-c5-envelopes-229x162mm-peel-and-seal-white-pack-of-100-551024--4
Tyvek C5 Envelope 229x162mm Pocket Peel and Seal White (Pack of 100) 551024 - Office Monster
The unique fibre structure of Tyvek security envelopes, developed by DuPont, is tear and water resistant for extra security during transit. The envelopes also...