elenbanggood For 450 Pro V2 or V1 frames it is 118mm. For 450 SE V2 it is 115mm. But with a little effort you can use a 118mm shaft if it has a separate collar and not a fixed one. For Sport V1 frames it must be 115mm if I remember right. The shorter main shaft is only for DFC heads. So a general rule applicable to all frames: Use whatever main shaft length was the original one. The flybarred and the flybarless head use the same shaft. Only the DFC head needs shorter than the original

elenbanggood I use it on Trex 450 SE V2 clone. So it works for clones also and for older design frames as well. I use the standard 115mm main shaft of the 450 SE V2. Why it should not work for clones? Only the ball links would make a problem but most clones have standard size balls.