4pcs Door and Window Lock This is a patio sliding door safety lock, prevents windows from being opened accidentally, extra security for your child and your window. Suggest the blocks are mounted high and low for maximum security, update your home security system. 8 Universal Keys Come with 8 universal keys, there are 4 sliding locks. Each sliding lock comes with 2 keys, the keys are universal. Zinc Alloy Copper Zinc alloy, anti-rust, durable and quality. Easy to InstallEasy to install, easy to use padlocks come with all security hardware, including stainless steel screw caps. Application Suitable for most swing or sliding doors and gates, this design is very useful for homes, schools and other places for children.