OPERATION: These security window locks allow you to limit the opening of a window to less than 100mm for safety and security. One unit of the PVC window restrictor is applied to the window frame or mullion, while the second is attached to the movable window, providing control over the opening. QUALITY : XFORT window limiters for PVC have been designed to withstand forces of more than 1000 N (100 kg) while the industry standard is only 50 kg. Both the locking system and the key are resistant to oxidation and corrosion to prevent damage or wear. SECURITY: This window lock protects your family and acts as a deterrent against burglars. The windows limited opening can prevent a child from getting in or falling through the gap. It can also be used to circulate air without allowing pets to enter or leave the house. The child lock can be unlocked to allow access to the window in an emergency. APPLICATIONS: This security door lock can be used on all types of windows and doors, including UPVC, aluminum, wood and metal profiles. Child window safety locks can also be used on fire escape windows, as long as the keys are close at hand.