i've only recently been told what one is so here goes. first a ball with the pin out 2-3" and appx. 2.5-3.5oz. of top weight works best. the pin is placed in the center of the grip and the cg and/or mass bias indicator and the x-hole are all placed on the same line at a 45 degree angle. the x-hole will be 6 3/4" from the grip center and should be as large as possible and extend deep( 2.5-3" )into the core of the ball. this type of drilling pattern gets the ball into a earlier heavy roll with a continuous backend reaction. great for lanes that are wet/dry.