D850-132 vertical lift drums for doors up to 11 feet tall. Capacity is 425 pounds per drum and they take 3/16-inch max cable. Sold as a matched left/right pair. Vertical lift setups are different from standard lift because the door travels straight up and the cables have to wrap around the drum in a specific pattern. Cable length formula is floor to shaft center plus 150 inches, minus door height. When your existing cables are a mess or the drums are worn and the cables keep jumping grooves, it is time for new drums. Verify your door height and that you are actually running vertical lift track, not hi-lift.