Our polythene envelopes are 'Mail Tuff' branded durable mailing envelopes. They are an ideal way to despatch non-fragile items. Manufactured from co-extruded polythene film, highly resistant to tearing and punching. Gives products protection from water and the elements. Much stronger than paper, card, or single layer film envelopes. All bags have a self-seal strip which is tamper evident.