You wire Apexi Multi Checker in at ECU end. It has a brain box, loom and handset. It displays speed, RPM,
injector use %, air flow %, ign. timing, engine power, eng. torque, A/F ratio. It also has a few alarms. I had it running in our car. Removed when Vi-pec fitted. I haven't posted a pic here for years. I can email (easier). PM.