The needle, powered by trigger action, strikes all the cylinder bottom pins simultaneously.
As the force is transferred to the upper pins, they momentarily rise in the chambers and create a wide gapping shear line.
At precisely that moment, with pressure applied on the tension wrench, the plug turns to the opening position!
Various amounts of pin striking action is achieved by merely adjusting the knob.
Comes complete with 3 steel needles and tension wrench.