... gas pressure sensor inside, the gauge sends pressure signal to fuel changeover switch, so that the driver ... you car, so that the gauge can be used longer.Specification:1. Type: YRF 2. Accuracy rating ... humidity: ≤80%9. Wire connection: white wire ,output signal red wire , positive Voltage black wire, negative Voltage10. Certification ... red light on switch lighted. Used in automobile waterproof gas meter