4PCS Window Door Locks for Kids4PCS Sliding Door Locks with 8 Universal Keys, each sliding door locks comes with 2 keys (the keys are universal). Easy Installation Supplied with all security fixing accessories including stainless steel screws. (Attention: Drilling is necessary; The white cap is used to decorate the hole made by the electric drill.) Zinc AlloyMade of zinc alloy, copper, anti-rust, durability and quality guaranteed. Child Safety LockPrevents accidents due to open windows and unlocked doors, helpful to protect your children. Suggest the locks be adjusted up and down for maximum security. ApplicationSuitable for most hinged or sliding doors and windows. Perfect for home, public, hospitals, hotels, schools and other children's places. How to use 1Measurement Measure the gap between inside and outside Windows (should be less than 1cm); Measure the width of the window frame (should be more than 2.5cm). 2Without the key, you can press the lock cylinder to lock directly.