RH228VC Bulldog Extreme Max rotary hammer drills holes up to 1 1/8-inches in diameter. Enhancements include a longer piston and impact bolt, combined with a precision-machined striker, which Bosch says increases the hammer’s speed and power. It delivers fewer blows per minute—up to 5,460—and puts less wear on the 8-amp motor. By creating a longer air cushion between the piston and the striker, vibration was reduced. The RH228VC has variable speed operation (0-1,230 rpm under load) and three operating modes (hammer, drill and hammer/drill).