M12x1.25mm nut for rotor and pulley on the crankshaft. Also in use for Minarelli AM clutch nut. Suitable for all special cranks with M12 thread for Piaggio and Minarelli engines. E.g.: Stage6 R/T, Polini Evolution, Malossi MHR Team Of course it also fits on original cranks with M12x1.25mm threads. Ref Flange Nut M12x1.25 150GS-E09.19 , GB6187-1986