ISR Performance OE Replacement SR20DET O2 Sensor - Skinny 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 Red top Sr20det utilize the Skinny type 3 wire plug O2 sensors, also S14 SR20DET's use the Fat type Sensor and not the Skinny type. 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 **