Beagle, if I remember right the adapter is 1/4 for the frio 10 I run that on my EStarter with a 8x4 prop, I would think that a folder in that general range would work good, mine tends to draw a lot of amps with anything over 9" on prop dia, I have a glider with a 5.4' WS that I'm going to put the same motor on and I'm going with a 9x4 or 6 folder and 3S 2200 lipo