Envelopes
Tyvek X/Str Gus Env E4 Wht - TY02274
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 closure...
https://www.bizrate.co.uk/envelopes/tyvek-x-str-gus-env-e4-oid27579602047.html