FUNCTION: These window security locks restrict window opening to less than 100mm for safety. One PVC window restrictor unit attaches to the window frame or sash, the other to the moving window, controlling the opening. QUALITY: XFORT PVC window restrictors withstand forces exceeding 1000N (100kg), surpassing the industry standard of 50kg. The locking mechanism and key are oxidation and corrosion resistant, preventing damage and wear. SAFETY: This window lock protects your family and deters burglars. The limited window opening prevents children from reaching in or falling through. It also allows air circulation without letting pets escape. The child safety lock can be unlocked for emergency access. USES: This security door lock works on all window and door types, including UPVC, aluminum, wood, and metal frames. It can also be used on fire escape windows, provided keys are readily accessible. EASY INSTALLATION: These window security devices are surface-mounted for easy installation by anyone. XFORT PVC window locks come with all fixings and accessories, including screws and a key.