Upper circle diameter: 8 cm; Inner circle diameter: 4 cm, so be careful that the screw end does not exceed 4 cm. Set details: 4 pressure screws; Length 8 cm/3.15 inches. M10 screws. White. They are ideal for child safety gates, pet gates, etc. They will prevent your children or pets from leaving the safety area. Material: The main body is made of high-strength and durable ABS plastic. The bottom is equipped with high-quality flexible PE rubber mats to avoid leaving marks on the wall. Non-slip: The soft rubber skate is non-slip and clings to the wall to prevent the door from sliding. When your pet bumps or even shakes it, you no longer have to worry about the door moving. Multifunction: Cups of pressure door safety gates are used in many types of pressure doors, such as: child door, baby safety door, baby gates, baby gates for stairs, pet doors with doors, baby door, tensioner, child gates, shower tension rod, etc. Wall cups can be used for shower curtains with tension mounting rods. Quality Material: The M10 pressure barrier consists of a steel core and ABS plastic. Sturdy and reusable. White ionized zinc screw for a clean aesthetic. Easy to Install: Our screw comes with adjustable length bolts. No tools are needed. No holes to make in the wall. These shoulder rods function as factory screws. Just twist; nut to create an opposing force against the wall for quick and easy installation.