This standard-duty pneumatic door closer uses air pressure to provide sure, silent closing. The door closing speed is adjustable, ensuring that doors shut securely every time. The seasonal adjusent options allow you to swap between window and screen on your door. Ideal for doors up to 1-1/4" thick, 30 to 50 lbs. The door closer measures 1.25� in diameter by 10.5� long. The SK9 includes all necessary brackets and screws for installation and is easy to install using the existing holes on your door. To protect your door and the door closer, a storm chain is recommended.