Longer jaws grip better, avoiding slippage or nut round off. Measurement scales (inches on front millimeters on reverse) are handy for sizing nuts, pipe and tube diameters. Greater jaw capacity supports larger nuts and bolts. thinner jaws for greater access in tight spaces. Precise jaw design grips tight the first time, every time. 4 thread knurl & non-protruding jaws provide greater capacity; minimal head width improves performance in confined spaces. Black phosphate finish.