ISR Performance OE Replacement SR20DET O2 Sensor - FAT ISR Performance O2 sensor are a great replacement for the worn out ones that often comes with the used SR20DET motors. Its always best to replace it to improve your gas mileage. For S13 Black top Sr20det utilize the FAT type 3 wire plug O2 sensors, also S14 SR20DET's also use the Fat type Sensor. To be safe, please look at your O2 sensor to determine which type you have and order accordingly.   ** All ISR Performance Products are Designed for Off Road Use Only **