Sold in a system that includes WEGO III Wide-Band Exhaust Gas Oxygen Sensor Interface, 42" harness, Bosch LSU 4.2 five-wire wide-band oxygen sensor, 18x1.5mm weld nut for mounting sensor on exhaust pipe and software on CD ROM WEGO III data logging software runs under Windows ME/XP/Vista; software allows AFR, engine rpm and analog sensor data with user-defined scaling; data can also be exported to Excel for further analysis Displays AFR (air/fuel ratio) and logs more than two hours data including AFR and engine rpm; spare 0-5V analog input for sensors such as throttle position or manifold pressure Wide supply voltage range from 11-16V allows operation from battery on small engines and race vehicles without an alternator; current drain is approximately 1 amp Waterproof, ultra-bright, daylight-readable blue LED display with automatic dimming under low-light conditions Can be used for on-road or dyno testing; suitable for motorcycle and other small engine applications Highly accurate with less than +/-0.10 AFR error over 10.3-19.5 AFR range Easy free-air calibration procedure corrects for sensor aging effects Complete fuel/air ratio metering system with built-in data logging 0-5V analog AFR output for interface to dyno instrumentation Compact size: 4" L x 2" W x .5" H Made in the U.S.A.. SENSOR WEGO3 AFR