Spline shafts are shafts that have a starlike shape that interface with motor hardware easier than other options like keyed shaft.
Motors that support Spline shaft are Kraken X60 Neo Vortex and the Falcon 500
Keep in mind these motors have different types of spline shaft, including a different diameter and tooth count. Pinions that work on the Kraken will not work on a Falcon (instead it will damage it!).
