Himax 4.0mm Hollow shaft with one collar, set screw and spring. For HC 2816 series outrunner motors. This shaft also replaces MPIHC2816-5. The hollow shaft is the only avialable part for a 2816 motor and the correct factory replacement according to MPI. 48.5mm lon, 4 flats. SKU Number: MPIHC2816-11