Due to extremely high pressure and uncertain fuel quality, the factory injectors in your LMM Duramax can fail over time. Especially if you're experiencing some white smoke and/or a hard start, you're probably due for at least one injector. If you're in need of replacing one, two, or all eight of your injectors, these are a genuine Bosch, brand new (not remanufactured) replacement injector. And because these truly are brand new, there is no core charge and no need to send in your original injector(s).