Material Made of high quality material. EXCELLENT SAFETY High quality choke cable increases home safety, health and safety, and baby/child safety. Easy to install Made of steel wire, with self-drilling screws and wrench, just a screwdriver or drill bit to install. Ideal for extensive use of PVC, aluminum, wood, composite doors and windows. For double-hung windows, casement windows and sliding windows; balcony doors, guest room doors, etc. There is a limit to how far the windows can be opened when the cables are in place. Using a wrench, you can remove the cable from one end and open the window completely. The shape is novel, the lines are smooth, and it can be bent at will. The unique lock cylinder greatly increases the security of the door lock. Package contains: 4 pieces