Material: The main body is made of high-strength and durable ABS plastic. The back is equipped with high-quality flexible PE rubber pads to prevent leaving marks on the wall. Wall Protection: These wall protectors are designed to safeguard your walls, doors, and staircases when installing baby gates or pet gates. No tools are required for installation, easily protecting walls, doors, or stairs. Non-Slip: The soft rubber skid is non-slip and adheres to the wall to prevent the gate from sliding. No need to worry about the gate moving when your sweet pet bumps or shakes it. Multifunction: Bumper cups for child safety doors are used in many types of pressure doors, such as: child door, baby safety door, baby gates, baby gates for stairs, pet doors with door, baby door, tensioners, child doors, shower tension rod, etc. Wall cups can be used for shower curtains with tension rods. Upper circle diameter: 8 cm; Inner circle diameter: 4 cm, so please be careful that the end of the screws does not exceed 4 cm.