HEDMAN STANDARD DUTY EXHAUST HEADERS, BLACK-PAINTED -- 49-state legal; Not for sale or use in California; Cannot be shipped to California addresses; 1.5 in. tube diameter, 18-gauge tube wall thickness, 2.5 in. flange collector, 0.25 in. standard head flange; Premium gasket and installation hardware included; Without smog injection or injection heads; Shorty style; Square head port; They feature 18-gauge mandrel-bent primary tubes; Protected by factory applied black paint for pre-installation protection; Made in the USA; Modification to stock exhaust required to retain catalytic converter; For vehicles 1964 through 1974 without A.I.R. systems; Considered as OEM replacement parts when existing emission controls are not removed from vehicle.