Featuring tamper evident locking flaps, which once inserted cannot be opened without causing considerable damage to the cardboard envelope, these white, carton envelopes are ideal for safe posting. For extra security, why not seal the envelope with one of our packaging tapes? Each mailer is manufactured from 350 gsm micro-flute corrugated board which helps maintain the structure & rigidity of the envelope & also has an attractive white finish. This board keeps your products flat & free from creasing during posting & will protect from day to day wear & tear. Reinforced corners also provide extra protection for your products. The expandable edges allow the cardboard envelope to increase in height by up to 40 mm, meaning that you can use these cardboard envelopes to post a variety of different products including DVDs, CDs, books, catalogues & calendars. If you want to discuss your packaging requirements with one of our experts call 0800 542 44 28 today, & get next day delivery. Sold in packs. Quantity Available in packs of 50 or 100 depending on the size of the envelope. Please see our discounts for 3 or more packs if you want to order in bulk. Size & shape options There are 3 sizes available of these carton envelopes with locking flaps; 440x 320mm, 530x 430mm & 670x 520mm (internal opening x height). Materials These carton envelopes with tamper evident locking flaps are made from 350gsm micro-flute corrugated board with a clean white finish. Environmental information 100% recyclable. Delivery information Delivered sealed in cardboard boxes to protect from dust & dirt.