Inserts for the APC props. With 1/4 inch shaft on the Jett as js3 mentioned, no problem but when you drill or ream for the 5/16 Nelson its difficult to get the hole perfect for balence purposes. If you look in the shaft hole in an APC pylon prop you will find that the 1/4 inch size only goes half way through the prop with the other half a larger hole. These inside diameters are accurate for our purposes but when you drill or ream the smaller diameter to 5/16 it is difficult to maintain that holes accuracy. The inserts are perfectly machined to fit a nelson shaft and that larger inside diameter on the prop. Using the rings will maintain balence much better than drilling or reaming. The insert stays on the engine untill time for disassembly so its a simple matter to drill out that small hole to clear the shaft and the accurate larger hole fits perfectly over the insert ring. Cheap and worth doing.

I use a radio south pro driver with the metal aligator clip that darrol sells. The pro driver is wonderful an uses instant varable current automatically will clear out a flooded plug with no imput from you. A valuable tool for the racer who has one minute to start, needle and get into position for takeoff.

John