Genuine Parsun locknut m6x0.75 166F-010011 is compatible with Yamaha 7FK-12158-00
Ships from Sweden next business day and should be with you within a week
2 pieces "locknut m6x0.75 166F-010011" are being used on the page "F5A/F6A cylinder head assembly"
They are sold one by one, if you need a complete set you need to buy multiple.