This CAT remanufactured C7 fuel injector includes a new, unique trim code with each injector. All O-rings have been replaced, and injector comes with a 90 day, no-hassle warranty. and has a 12 month, unlimited-mileage warranty. There is 100% surface lapping of critical components. There is an additional core charge of $275. You purchase your fuel injectors from us and pay the core charge up front. We allow you 30 days to send your core injectors back to us. MUST ADD ACE PRODUCT CODE # 9FI634761COR to the order.