One-piece 8-foot belt assembly for LiftMaster and Chamberlain belt-drive openers, part number 41A543413. Fits 8-foot residential doors only. If your opener's been slipping, making noise during travel, or the door stops short of fully opening or closing, the belt's probably stretched out or the teeth are worn. Don't try to use a 7-foot belt on an 8-foot rail because it won't reach. And a 10-foot belt is too long. Match the part number to your opener model before ordering since LiftMaster uses different belts for different rail generations.