The High Sliding Door Child Lock is a child proofing lock that keeps kids from opening sliding glass doors that lead to dangerous places. Easy to install, it stops the door at a four-inch gap from the frame so that parents and caregivers can let air in, but keep children and pets in, too! This provides ventilation but stops the child. Simple to mount and easily utilized from either side of the door, it offers easy disengagement for adults and its red and green indicator tells you when the lock is in use. Non obtrusive design.