"Trolley is dependable, easy and safe to use. Capacity lbs. 6,000, Includes Sealed ball bearing wheels, Material Type Steel, Works With Any S, H, W, M type I-beam, Flange Width in. 3 to 7 1/2. 10.375in. headroom Width is adjusted with manual screw mechanism Locking ring prevents trolley width from changing accidentally Manual screw mechanism may also be tightened to prevent trolley from moving similar to a Beam Clamp Includes four smooth rollers with sealed bearings for long life Lifting eye is located at the bottom of the trolley for attaching a hoist sold separately Painted finish"