Just to give you guys some idea of how strong the 648 green is, on my 64" bonzi with a pair of full mod 260's inline building over 15hp on 20% nitro, I can twist the 1/4" hardened flex shaft in half by blipping to full throttle, and on the past 6 broken shafts iv used the green on the stub, and have yet to have a failure at that point.