The Circuit Hero Digital A/F Gauge w/ Bosch® 4.9 LSU Sensor accurately measures the engine's air/fuel ratio .  Using a wideband air/fuel controller during the tuning process allows you to monitor AFR and adjust tuning parameters to optimize them for maximum power and efficiency. Our sensors are individually laboratory-calibrated by Bosch and never require calibration.FEATURES4.9 LSU Sensor with Weld-In Bung Included52mm (2 1/16”) Gauge Housing Display Output from 10:1 to 20:1 AFRLED Display w/ 3 Color Sweep from Red, Yellow, Green Accuracy Down to 0.001 with a 4 Digit Display0-5 Volt Output for ECU, Dataloggers, etc. The Circuit Hero Digital A/F Gauge w/ Bosch® 4.9 LSU Sensor accurately measures the engine's air/fuel ratio .  Using a wideband air/fuel controller during the tuning process allows you to monitor AFR and adjust tuning parameters to optimize them for maximum power and efficiency.Our sensors are individually laboratory-calibrated by Bosch and never require calibration.FEATURES4.9 LSU Sensor with Weld-In Bung Included52mm (2 1/16”) Gauge Housing Display Output from 10:1 to 20:1 AFRLED Display w/ 3 Color Sweep from Red, Yellow, Green Accuracy Down to 0.001 with a 4 Digit Display0-5 Volt Output for ECU, Dataloggers, etc.