"Trolley is dependable, easy and safe to use. Includes Sealed ball bearing wheels, Capacity lbs. 8,000, Material Type Steel, Works With Any S, H, W, M type I-beam, Flange Width in. 4 to 11 3/4. 13.875in. headroom Width is adjustable with manual screw mechanism to fit beam flange widths 4in. to 11.75in. Includes four smooth rollers with sealed bearings for long life 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 Lifting eye is located at the bottom of the trolley for attaching a hoist sold separately Painted finish"