RSM's props are very nice and come balanced. At least, the only one I have run was perfect out of the pack. They are made to RSM specs, chords, pitch distributions, airfoil, etc., by XOAR in PRC. I would expect XOAR props to be similarly well made and balanced. I think there are other brands that are made by XOAR, but haven't any proof of that. Zingers are most definitely not made by XOAR!!!
Steve