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 300 rpm or 600 rpm operating speed. The 4004 has a clutch to protect gears and motor against overload. This unit will handle core bits from 4 in. to 14 in. in diameter.