Diamond coring motors are used with Vac-U-Rig and Dymorig diamond core rigs to drill holes into reinforced concrete. This 20 amp model features 4.8 peak horsepower with a 450 rpm or 900 rpm operating speed. The 4094 uses a shear pin to protect gears and motor against overload. Shear pins are easily replaced and extra pins are included with the unit. This unit will handle core bits from 2 in. to 10 in. in diameter.