In general, the second trolley works best on lifts mounted in spaces with ceiling heights of 9 feet or more. In shorter garages, the lower trolley will not lift very far off the ground before the upper trolley stops at the ceiling.
The double trolley comes with a 24-inch cable that hangs from the first trolley and spaces the hitch receivers about 32 inches apart. If you need a different spacing, contact Top Shelf’s customer service and ask about custom length fantastic cables to fit your needs.