And Master Airscrew from Windsor Propellers. I buy the 6"x3" GF series for my glow planes and cut them down to 5.5", 5.25" and 5". The only plane I use a 6" prop on is a 5.5oz stunt plane with a Norvel .061, just to tame it so it's not too much of a rocket around the circle. MA props balance easier than the Cox props too.

http://masterairscrew.com/gfseriespropellers.aspx