The RH540M SDS Max combination rotary hammer from Bosch provides maximum productivity in all day drilling and chiseling applications. Equipped with 6.1 ft./lbs. of impact energy (E.P.T.A.) The RH540M provides up to 39% more impact energy versus the previous model for best in class performance. The RH540M also provides variable speed. This delivers better bit control during application start-up.