a ball that has the "pin in" means the pin( the top of the weight block ) and the cg( center of gravity ) are less than 2" apart. this ball will get into an early roll. a "pin out" ball means the pin and cg are at least two inches apart---and usually more. this ball will skid farther and flip harder on the backend. a pin out ball also lends itself to being more versatile in regards to drilling patterns that can be used.