These door locks work well on most wood, glass, plastic, and metal surfaces. No tools are required for installation. Just remove the backing from the pre-installed industrial strip. Additional soft TPR rubber has been placed on the contact surface to protect the door or window from scratches. It is super easy for adults to maneuver and use, but quite complicated where children and pets cannot go through at all. Non-toxic and tasteless. These locks are absolutely safe for children and durable to ensure your child's safety and security. This invisible baby padlock is made of environmentally friendly plastic materials. Imports double-sided tape, super viscous, close-fitting furniture, easy care. No key needed, door lock easily with a simple flip lock. Stable triangular structure prevents the door from sliding, easy to install and remove with a little breath. Specifications: Color: white Material: plastic Scope of delivery: 4 invisible baby padlocks