w/ black mark - - Injector w/ black mark. - Injector w/ black or yellow mark. - Injector w/ blue mark. Hitachi is currently only offering the black mark version of this injector. If the vehicle has blue mark injectors, the black mark version will perform correctly if all of the injectors on the cylinder head are changed from blue mark ones to black mark ones. We may still have a few of the OE Service injectors with blue marks for those who wish to replace just one or two. - Injector w/ blue or white mark. Hitachi is currently only offering the black mark version of this injector. If the vehicle has blue or white mark injectors, the black mark version will perform correctly if all of the injectors on the cylinder head are changed from blue or white mark ones to black mark ones. We may still have a few of the OE Service injectors with blue marks for those who wish to replace just one or two. -