This is not an exchange service. You send your injectors in to be rebuilt and receive back the same injectors that you sent in. You know the history and mileage of these injectors. These get all the major wear items replaced such as nozzles, nozzle lift spring, piston return spring, all seals and gaskets, spool valves polished and all sealing surfaces are refinished. These are all bench tested on our Hartridge HA-230 flow bench once completed to ensure all flow rates and functionality. These include a 6 month warranty. If your injectors cannot be rebuilt with this service we will contact you for options and proceed from there. We always recommend especially on larger injectors to go with our Premium Remans. With all new parts in them they are naturally more reliable and will have better longevity.