Replacement belt for LiftMaster and Chamberlain belt-drive openers, part number 41A543414. This product is a one-piece 10-foot belt assembly, so it is specifically for doors that are 10 feet tall. When your belt's worn, stretched, or has teeth missing, the opener slips and the door will not 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 are not universal across all LiftMaster units. Check your manual or the old belt's part number before ordering.