It depends on what you want. If you want the engine to pull like a tractor, the APC 12 1/4 - 3 3/4 is the prop for you. General overall flying, the 12x6 is a good choice, but I like to take advantage of the 4 strokes ability to pull and I am not one for speed, so the low pitch APCprops work very well for me. Ithink you could even swing a 13x4 without issues. If you want speed, then lower the diameter and up the pitch.

I bought a couple dozen 12x6 wood Zinglers on Ebay when I first started flying, They were cheap and when I was going through two to three props a day, it was a good investment. I finally settled in on the APC 12 1/4 x 3 3/4 fortwo reasons. The added prop weight let the engine idle down with a more reliableslow idle around 2000rpm. It also allowed me to yank the plane out of trouble with thequick spool up of thefour stroke and theawsome pull of the wideblade,low pitch prop.

It really depends on what and how you want to fly. The engine is a very good choice, I'm on my second one and it seldomgives me any problems and those are quickly resolved.

Don