3 in 1 multi-function and easy to use: This is a tire pressure gauge to accurately monitor tire pressure; It is also a tire inflator for inflating tires when connecting an air compressor. Additionally, it has a built-in air bleeder valve that quickly lowers the pressure of over-inflated tires. High precision: Professionally calibrated to always give you a reading within 1% of the exact pressure of your tire and 0.1 in display. No more surprises! Accurately measures 0 to 250 PSI (0-17.2 Bar; 0-1724 Kpa; 0-17.5 kgf/cm²) WATERPROOF SHUT-OFF CHUCK AND VALVE EXPANDER: The Air Chuck Quick-lock (push-fit gas interface) provides an excellent seal on the tire valve outside the car tire and frees your hands to operate the tire pump. Long service life : Made of high quality and robust stainless steel and brass components to give it a very long lifespan. Can be used with all vehicles, such as car, SUV, truck, motorcycle, bicycle, etc. Easy to use: automatically turns on and off after 20 seconds of inactivity so preserve your battery; Built-in air bleeder valve to quickly reduce pressure in over-inflated tires. 250PSI HIGH PRECISION TIRE INFLATION GAUGE Measuring range: 0-250PSI p> Accuracy: ± (1% + 0.1PSI) Four ranges: PSI, BAR, KPA, KG/CM^2 How to use: 1. Unscrew the tire valve knot. 2. Attach the copper head of the gauge to the valve 3. The device will show the pressure. 4. You need to find an inflatable gas pump and pipe to connect the inflatable mouthpiece and hold the product handle. Inflate it through the inflator，when the pressure is low or vice versa. 5.After measurement, unscrew the copper head and press the air vent so that the indicator is at 0.