Protective cover screw is also known as a protective cover screw protective cover, which can effectively protect the screw, light bars, shafts, columns and other parts from dust pollution and destruction of substandard special, able to do with the components stretched or compressed motion, can be used either vertically or horizontally. Levels is recommended when using plastic or aluminum support ring, holding shield cavity and screw to prevent iron and other foreign objects wrapped into the screw, lead screw causing friction and blockage of screw drive, thereby affecting the movement of the machine, screw blocked even a glimmer will not contact Sun Shiqiang Mobile Phone 0317-6341612 15690271367 Website www.ysjrjcfj.com mail 2227130514qq @. com