Here is what I have learned with my 4-strokes. I tried to use the plastic spinners once. The engine backfired and kicked everything off and in all different directions. This was enough to sell me on a tru-turn. I think of it this way, it's not a $200 arf that this is going on, it's a $200 engine and mine and others safety. Those plastic spinners don't hold up for crap on 4-strokes. Chincing up on the device that holds the prop from coming off is not worth it to me.

I have used the Great Planes aluminum (which are much cheaper than tru-turn) and they were fine and there are also alot of cheaper ones out there. I see polished aluminum ones in the magazines all the time from this one company, and I cannot find that as right now, and I think a 2 1/2" was like $17 plus the adapter..That's not too bad considering what could happen with those cheap plastic ones and your hand or body in the way when it kicks off an APC prop...