well~ there are a variety of balls to use, like eleven inch and twelve inch balls. If you're coaching mens softball, I suggest the twelve inch ones.

thank you

Slowpitch or fastpitch?

also need to know what sanctioning body you are playing under. ASA has different requirements than does USSSA

most leagues require 12" .375 lbs 44-core ball, but even then some leagues have other stipulations. for example, some ASA leagues ban the gold dot balls and others don't. check with your league rules before purchasing

you should play ASA league and use a yellow 12" ball