Simple, rugged, built for trouble-free service and easy of operation across a wide range of beam applications. The 633 features rugged steel sideplates formed to include bumpers and trolley guards. Opposing frames are connected by steel equalizer pin, which is secured by two nuts on each side. Universal tread flanged trackwheels are equipped with shielded ball bearings. Hardened wheels and axles for added strength and durability. Spacer washers can be shifted inside our outside for easy adjustment to wide range of beams. For use with a hook-suspended hoist (suspension plate for easy attachment is standard). Bearings pre-packed with lifetime lubricant for maximum service life. Lifetime warranty.