This is a full set of (8) new high performance cylinder head nuts with built in washers. These fit all air cooled models of Honda N360, N600 and Z600 Sedans and Coupes. Includes six open and two closed end nuts. The closed end are for the studs that flow oil up to the head just like the original acorn nuts.These nuts are over twice as strong as the original Honda nuts. It's the same quality material that is used on Super Race Bikes.