The Light Rail 3.5 runs by a self-propelled 6 or 10 rpm motor; no pulleys, chains, or gears. Ideal for rectangular growing areas or aquariums. The 6 ft rail can be expanded to 9 ft and has adjustable switch stops to enable various travel lengths. The Light Rail 3.5 Intelli Drive travels at approximately 2 ft per minute. The adjustable Intelli Drive time delay feature enables your lamp to pause at each end of the track for 0-60 seconds. The Add-a-lamp kit allows you to expand the system from 6 ft to 12 ft, moving two reflectors in-line with one motor.