The Matthews Studio Equipment Chain Grip provides maximum gripping power on any size pipe up to 6" in diameter. The Locking Pliers also provides maximum gripping power on both flat and round surfaces with smaller diameters. EXTREME CAUTION must be taken when the 5/8" pin provided on the adjustment screw is used. Be sure that any off-center weight is toward the locking direction (clockwise); allowing more weight on the other side could loosen the jaws.