The Chicago Pneumatic CP 4611 is used for concrete demolition and has become one of the stars of the CP range. Also known as the Hell Dog or Boyer Buster, the rivet busters have a low-frequency blow with hitting power equivalent to a paving breaker twice its weight. The new CPS includes a stepped piston and steps cylinder to prevent accidental ejection of the piston. Originally designed for cutting and forming metal rivets, the CP buster is now used for concrete demolition and has become one of the stars of the CP range. It has a low frequency blow with hitting power equivalent to a paving breaker twice its weight. The new CPS includes a stepped piston and step cylinder to prevent accidental ejection of the piston. Features: Teasing throttle for progressive hitting frequency gives better control of such a powerful machine Special Boyer valve makes the cylinder stroke effectively longer for more hitting power Boyer valves high quality design makes the blow more consistent Forged steel handle for long life in rugged conditions Stepped piston of hardened steel Stepped piston to prevent accidental ejection of the piston New buffer ring is now 90 durometer rubber for extra life Choice of cylinders: 11 cylinder (720 bpm) 8 cylinder (1080 bpm) Choice of handle: Open grip with outside trigger D-handle with inside trigger 1/2 inlet bushing