Used on all later Forster engines with ratchet spring. Forster used 2 different size needle wire diameters, .062 and .065 We assume they did this because of 2 different size spray bar holes which may have been a mistake during production in the 1950's We supply the .062 for replacements which will fit either spray bar. You may special request the .065 but no returns on the .065 size.