Material Made of high quality material, can withstand higher pressure, not easy to damage. Excellent safety High quality choke cable for increased safety, health and safety in the home and baby / child safety. Easy to install Made of steel wire measuring 19cm long, comes with self-tapping screws and wrenches, just a screwdriver or drill to install. Widely used Ideal for PVC, aluminium, wood, composite doors and windows. Use on double-hung, louvre and sliding windows; balcony doors, guest room doors, etc. Locked and unlocked Special restriction design provides 19cm restriction and fresh air, and the window can be fully opened when the cable is pulled out at one end with the wrench. Once the cable is in place, the distance the window can open is limited. With the wrench you can remove the cable from one end and open the window completely. New shape, smooth line, can be bent at will, cable distance up to 18.5cm. Unique lock core, greatly increased the security of the door lock. The package contains: 4 packs