Are you talking about the air/fuel controller or the system bypass module? The Cpe CAI comes with an air/fuel controller or you can purchase one separate. It comes in either tunable or non tunable versions. You can get a non tunable version specifically for the CPE and Injen cold air intakes. Then you can use the bypass module with either one. But you only use that if you have the air/fuel controller. The system bypass module isn't necessary for the CPE Mafci System or the CPE Injen Fix. Hope that helps and in the future do a search.