This is a popular conversion for older cars with a single wire O₂ sensor such as the 1985-93 TPI & LT1 vehicles.  By running a 12v switched power and a ground, the heating element in this O₂ helps keep the sensor at a stable temperature to help maintain closed-loop operation and give more accurate readings to the ECU.  This is a genuine Bosch sensor and comes with weather-pack kit for easy retro-fit on older cars.