Racers know how critical thousands of a second are when it's time for eliminations. With the PA-2 and PA2-02 with Oxygen Sensor, there's no more guessing. Features: date and time; temperature; humidity; barometric pressure; density or oxygen altitude; predicted E.T. or throttle stop setting. Also, with the optional oxygen sensor, you can accurately determine the percent of oxygen in the air! Incorporates a custom data entry/prediction keypad and a large display for easy readability.