Replacement belt for LiftMaster and Chamberlain belt-drive openers, part number 41A543414. This is a one-piece 10-foot belt assembly, so it's specifically for doors that are 10 feet tall. If your belt's worn, stretched, or has teeth missing, the opener slips and the door won't travel consistently. Swapping the belt is a lot cheaper than replacing the whole opener. Make sure your rail length and opener model are compatible with this part number because belt assemblies aren't universal across all LiftMaster units. Check your manual or the old belt's part number before ordering.