These Hexagonal nuts are the correct item fitted to all magnesium crankcased SOHC and early DOHC racing engines and are made as per the original design - i.e. 47mm Across Flats . This larger diameter nut allowed more 'holding area' than the small International nuts, probably because the Manx pins had less depth. - Price is 'per nut' - If you are not sure what type of nuts your engine should be fitted with : Earlier Manx Bigends (all SOHC\DOHC magnesium cased pre-featerhbed engines and earlier Featherbed engines) used large 47mm AF Hex Nuts. Later shortstroke DOHC engines used castellated nuts. I can supply both types. If you are not sure if your flywheels should be using Hex nuts - look for the 'Mickey Mouse ear' cutaways, for grub screws (see 2nd photograph), which signify it was fitted with Hex nuts. Wherever possible, if the engine was fitted with these larger nuts, you should try and refit them, as they provide a larger surface area than castellated or International nuts.