High Quality MaterialThe automatic spring buckle is made of stainless steel and zinc alloy. The one-piece molding process and the multi-channel assembly process make the whole product durable, rust-proof and have a long service life. Package ContentsAfter purchase , you will receive a door closer, 4 screws, an Allen key and a protective door seal. The stainless steel spring door closers are easy to install without having to purchase additional parts. [Adjustable Design] Increased adjustment force: adjust clockwise a by one, the product default strength is 2 gears, only 2 gears can be increased; adjustment force is reduced: just insert the L-shaped key into the long end and press hard to restore the minimum force. Noise reduction The door closer can reduce interference sound when the door is closed and close the door slowly to reduce the damage to the door caused by strong impact and prevent you from forgetting to close the door. Widely Used interior are suitable for metal doors, fire doors, wooden doors, civil doors and commercial doors, almost all doors under 30 kg. Self-closing adjustable doors are ideal for home, office and hotel room doors.