"The SOLAS Yamaha Type-D 50-100hp Fixed Hub Propeller Hardware Kit sets you up to install a new boat propeller (not included). This kit is built for SOLAS dual prop and B3 installations, and front and rear propellers must both be manufactured by SOLAS. Also, they must be made of the same material: either aluminum or stainless steel but not both. Special tools may be required. Kit includes castle nut, thrust washer, 2 spacer pins, and 2 cotter pins. This replacement kit from SOLAS fits with specific Yamaha Type-D applications, all with 4.25"" gearcase 15-tooth splines. Kit sets you up to install a new boat propeller (not included) Built for SOLAS dual prop and B3 installations Includes castle nut, thrust washer, 2 spacer pins, and 2 cotter pins"