Envelopes
Blake Purely Packaging C4 320 x 240 mm Polypost Security Polythene Mailing Bags (SE920/100) White - Pack of 100
Tear Resistant Perfect for use with Confidential Mail Peel & Seal closure for extra security Super secure Tamper evident
https://www.bizrate.co.uk/envelopes/blake-purely-packaging-c4-320-oid36970408295.html