Complete air/fuel ratio metering system with built-in data logging. Includes WEGOIII Wide-Band Exhaust Gas Oxygen Sensor Interface, Bosch LSU4.2 5-wire wide-band oxygen sensor, 18x1.5MM weld nut for mounting sensor on exhaust pipe, and software. Unit displays AFR (air/fuel ratio) For all carbureted and fuel injected engines, logs over 2 hours data including AFR, engine RPM, and has a spare 0-5V analog input For sensors such as throttle position or manifold pressure. Can be used For on-road or dyno testing. Highly accurate with less than 0.10 AFR error over 10.3 19.5AFR range. Easy free-air calibration procedure corrects For sensor aging effects. 0-5V analog AFR output For interface to dyno instrumentation. Wide supply voltage range (11-16V) allows operation from battery on race vehicles without an alternator. Current drain is approx. 1 amp. WEGO III data logging software runs under Windows 98/ME/XP/Vista. Built-in USB interface. Software allows viewing AFR, engine RPM and analog data with user defined scaling. Data can also be exported to Excel For further analysis.Size: 4L x 2W x 0.5H.