Echo the above. Balls that have a significant mass bias (asymmetric cores) have the mb marked. Those that do not have a significant mass bias (symmetric cores) do not. To find the theoretical mass bias on a ball with a symmetrical core, measure 6 3/4" on a line from the pin through the center of gravity. But it will be so small that it won't affect ball reaction, so you might as well just use the cg. -- JohnP