Diameter:9 7/8. Pitch:14. Rotation:Right. Spline tooth:10. Fits for outboard engine:Yamaha

20-30HP ​3" Gearcase ​20HP …1996-1997 ​F25(4 stroke)…1998-2006; ​2010-newer ​25HP …1980-newer ​30HP …1979-newer