The TIZIP WaterSeal is made from a strong plastic coil zipper on a high strength fabric. Every coil half is safely embedded and secured in a plastic profile. When the TIZIP WaterSeal is closed, the sealing lips above and below the coil are compressed making a perfect seal. The entire plastic profile is highly abrasion resistant. The unique design prevents the slider from wearing down the sealing lips when the zipper is opened or closed. for more info visit http://www.tizip.com/produkt.php?lang=en