The bore for the gear is 1.250" and the overall length is 2.200". This coupler can be used with all 1.250" 48 spline blower drive shafts but can be bored out to fit 1.50" register if the racer needs.
RBS stocks a full inventory of grade 8 bolts for the coupler if the racer needs #500-5012 for a socket head allen bolt or #400-5012 for a twelve point.
This coupler is designed to be used with a retro fit Littlefield, Blower Shop, Mooneyham, Kuhl, BDS or any other roots blower that may use a 2in. thick front bearing plate.