Premium Material: 304 stainless steel locks and 202 stainless steel screws. Corrosion resistant, high toughness, rust protection. Durable enough to protect your baby and kids Easy to install: just need a screwdriver to complete the installation (comes with screws). A window opener can be completed in about 5 minutes. Please note that the gap between the window and the window frame should be 14-17mm Maximum opening: The window can be opened normally if the window vent is unlocked. Once fixed, the window can be opened to 65 degrees. Effectively protects your child or pets from falling out of the window Wide Use: These UPVC window keepers are an ideal choice for home, nursery, school and more. Your safety is protected Contents: 1 left-handed and 1 right-handed door guard, including 8 necessary screws.