Heavy Duty Demolition Jack Hammer Concrete Breaker 1100w 15J Vevor Demolition Jack Hammer Concrete Breaker 1100w Electric Hammer 3 Chisel Bitheavy duty demolition jack hammer concrete breaker 1100w 15j. The seller is idavra1 and is located in this country US. Thank you for shopping at our store. Hammer frequency 3900BPM(RPM) Impact Energy 15J.