It is an electromagnetic valve that opens and closes to allow high pressure oil into the injectors. Replaces Part# 5C3Z9C968CA, 1846057C1, CM-5126, 5C3Z-9C968-CA, AP63417 - commonly found on popular F-250, F-350 Super Duty, E-350 and Excursion models with 6.0L V8 Diesel Powerstoke Engines including years 05, 06, 07, 08, 09, 10.