Schelle's 12mm Big Bore V2 Bevel Screw Mount Shock Pistons were developed for Associated Big Bore V2 1/10 scale shocks that use 'screw on' type pistons, and have a 45 degree bevel edge on the bottom side which allows for quicker rebound damping. Lighter rebound damping (rebound= extension) means that the shock can more quickly respond after bumps in the track, keeping the tires from hopping. Also on large jump landings, the lighter rebound damping keeps the wheels on the track as the chassis recovers from bottoming. This translates to added stability and consistency. These 2 x 1.7mm hole provide the least amount of damping in the Schelle Piston line, and are recommended for medium to low traction surfaces to deliver more grip when the car feels loose and when the track doesn't have large jumps.