Silver shim is 3mm and copper is 1mm you can run 30% with these shims. if you want you can take the copper out after breakin to run 20%.
STS keeps changing what comes with the motors. first ones came with all three shims for a total of 6mm then they changed to just the sliver 3mm now they put .4mm worth of shims in . I think they readded the shim to make breakin easier on you and the pullstart.
