High Quality Materials: Our automatic door closer's rod and arm are made of high quality zinc alloy and cold rolled steel, extremely strong and wear-resistant, and the wheels are made of rubber material, which opens the door silky smooth and softly without sound. Adjustable Speed Closer: The speed of this spring door closer is adjustable, you can use our complimentary strength adjuster to arbitrarily adjust the closing speed between 1-4 gears according to the specific use. Double Spring Construction: This automatic door closer is made of double spring construction, which is assembled by two springs, the spring force is enough to support 20-40kg door, both left and right door are equally suitable. Easy Installation: Our door closer is easy to install. You can follow the instructions to determine the mounting position, then fix it with screws, and finally install the strength adjusting lever and pulley adjusting lever according to your needs. Noise Reduction: The door closer can reduce the noise interference generated when closing the door, close the door slowly to reduce the damage to the door caused by violent impact, and can prevent you from forgetting to close the door.