Zipper slide degree is not the lighter the better, the smaller light slippery degrees, zipper slider manufacturer showed the pull head lumen side help to tooth chain you less imposed by extrusion, extrusion pressure small, pull head will not be able to make chain belt mesh each other, it will appear the phenomenon of chain tooth broken belly, light slippery degrees, of course, too much is not good, so head pulled up is very demanding. Zipper in the close process needs a proper extrusion, the force of pull head in chain belt drive, there is always a sticky, but very light slippery feeling again, which requires the pull head and chain belt, when fit, there is a proper, the size of the high precision, the ideal state is in the head with chain, not just pull a head of a fixed point and the tail chain tooth contact, but pull head inside the cavity side to help keep a line contact with chain tooth, this will reduce the pull head lumen side for protection of wear and tear, increasing the quality of life and stability of the zipper. In head to match the chain belt drive in the process, the size of the need to have a proper and precise coordination, the dimensional tolerance must be strictly controlled, it is also a zipper manufacturing process to ensure the quality of the product batch.