Our Polythene mailing envelopes range is stronger than manilla envelopes, yet lighter to post and water repellent. All the colour opaque polythene mailing envelopes have a flap and self-adhesive sealing strip which is non-releasable for tamper evidence and all open on the short side pocket style. The Polythene Mailing envelopes range would suit all your mailings and packaging requirements including both Amazon & eBay deliveries.