i bought a set of future f jc1 thrusters and i found a website selling the fin boxs so i can build my own board.

does anyone know why there is two size future fin box? a 1/2" and a 3/4".

http://www.foamez.com/fins-fin-syste...age=2&sort=20a

what would be correct for these jc1's?

thanks in advance.