1.1" Stroke Inside Trigger D-Handle. Uses round shank chipper steel. Tool designed to reduce handle breakage to a new level for foundries using a 4-bolt hammer design. Both inside and outside levers are available to suit the application needs. The unique two-step piston provides a large mass piston in a smaller, narrower tool. The MPT Mini 4-Bolt hits harder than any other mini chipping hammer on the market today.