This pair of 36 by 54 inch extension springs is made for 9-foot garage doors with clipped ends. Choose the door weight option that matches the actual weight of your door so the springs can balance the door correctly. The clipped end style gives the spring a secure connection to the track bracket, which many installers prefer over a simple open end. These springs are intended for doors that already use an extension spring system, and replacing both sides as a pair helps the door move more evenly.