This triple square bit socket set includes: M5 - M6 - M8 - M10 - M12 - M14 - M16 - M18, 1/2-inch Drive. The xzn spline bit socket set is forged from Cr-Mo Alloy Steel for its strength under the pressures of impact use and wear resistances, and is suitable for use on all air powered & battery powered impact tools. This triple square bit socket set with oiled, black oxide finish for maximum corrosion resistance. Pin hole at the base of each socket for use with a locking pin for secure attachment to drive tools. Size markings have been laser etched for quick and easy identification.