These door locks are suitable for most wooden, glass, plastic, and metal surfaces. No tools are required for installation. Simply remove the pre-installed industrial-strength adhesive tape on the back. The contact surface is covered with soft TPR rubber, which protects windows and doors from scratches. Very easy for adults to use, but more troublesome for children and pets who cannot get through. Non-toxic and odorless. Absolutely safe and durable for children, keep your children safe. This invisible baby lock is made of environmentally friendly plastic. No key is required, just a simple button can lock the door easily. The stable triangular structure prevents the door from sliding, is easy to install and remove, and is lightweight and breathable. Product Specifications Color: White Material: Plastic Package Contents: 4 Invisible Baby Locks