I just bought some alex 3/8ths wheels and I need to know what kind of freewheel to put on, I'm unfamiliar with the different types of hubs, sizes of freewheels (not tooth size) and what can go with what, or if it matters. Help would be much appreciated

ok so maybe i am out of it but whats an alex 3/8ths wheel.... and also what riding are u doing...most f/w fit on anything... so its not a big deal... like racing ones might have smoother bearings for ...well the obvious or like street or ramp riders enjoy there 3/16ths chains so we go with the big acs fat....i dunno maybe its the heat getting to me... hope it helps