In fact, it is not surprising that waterproof pockets, swimming pockets, can soak in water and stay in the water for a long time. This most critical component is the airtight zipper. The airtight zipper was originally a supporting product for space protective suits. It was originally developed by NASA to make high-altitude pressurized suits, and later used to make space suits, which can keep space suits in the vacuum of space air pressure inside. The airtight zipper is a kind of zipper with relatively high requirements on waterproofing among waterproof zippers, and is generally defined as a zipper with ipx8 waterproof performance.