This is a Starter Shaft for use with Nitro engines that have an internal one way bearing. It can be used as standard with XTM, SH, Force and Mach engines.
This can also be used to convert HPI 3.5, and K series 4.6 & 5.9 engines, replacing the original 9mm Hex shaft, and allowing a standard pull start to fit the engine.
Note, the HPI engines are high compresion engines, so a chrap pull start will not last long. For best results use the RCScrapyard guaranteed unbreakable, extar long pull start. Ebay item number is 284919778534
This will not fit Hyper 7, 21 or 28 engines.