Envelopes
Tyvek Envelope 406x305x50mm Gusset Peel and Seal White (Pack of 100) 758124
These Tyvek envelopes are made from 100% recyclable, high density polythene fibres (HDPE), which is tear and water resistant for extra security in transit. These envelopes have an expanding 51mm gusset and extra strong hot melt peel and seal...
https://www.bizrate.co.uk/envelopes/tyvek-envelope-406x305x50mm-gusset-peel-oid35492755054.html