Quality German-made engine glow plug, you will need 4 for your US-spec TDI (not PD engined cars). For all A3, B4, A4 (with ALH engine). NOTE - if Bosch plugs are out of stock and you don't want to wait, the Beru plugs are almost identical as they share the same patented technology. As long as you are replacing all 4, there is no discernible difference between the two. These are not the appropriate glow plugs for PD or IDI engines.