4pcs Door and Window Locks: This is a sliding patio door safety lock, which prevents windows from being opened unintentionally, extra security for your child and your window. Suggest blocks be mounted high and low for maximum security, home security system update. 8 Universal Keys: Supplied with 8 universal keys, there are 4 sliding locks. Each slide lock is supplied with 2 keys, the keys are universal. Zinc Alloy: Zinc alloy copper, rust protection, durable and quality. Easy to Install:Easy to install, easy to use padlocks come with all security accessories including screw caps stainless steel. Application: Suitable for most hinged or sliding doors and doors, this design is very useful for homes, schools and other places for children.