Material Made of , able to withstand higher pressure, not easy to damage. Excellent Safety High quality choke cable for added safety, health and safety at home and baby / child safety. Easy to Install Made of steel wire which measures 19cm long, comes with self-drilling screws and wrenches, just a screwdriver or drill to install. Widely Used Ideal for PVC, aluminum, wood, composite doors and windows. Use on double hung, casement and slide windows; balcony doors, guest bedroom doors, etc. Locked and Unlocked Special limiting design provides 19cm of restriction and fresh air, and the window can be opened fully once the cable is pulled out for one end using the wrench. When the cable is in place, the distance that the window can open is limited. Using the wrench, you can remove the cable from one end and fully open the window. New shape, smooth line, can bend at will, cable distance up to 18.5 cm. Unique locking core, greatly increased the security of the door lock. Package included: 4Pcs