Gauge Operation LCD Shows Pressure & Unit of Measure Press ON button to turn gauge on. NOTE gauge MUST be turned on before applying pressure because it captures zero pressure at power on. The gauge turns off automatically if no pressure is applied within 15 seconds. The only way to turn the unit OFF is to wait 15 seconds for auto-off feature. Battery Replacement Approx. Battery Life is 5 Years so the need for battery replacement should be very limited (Depends on usage) Remove protective rubber boot. Remove both screws in back of case. Remove and save sealing tape around outside of case. Separate case to expose battery. Slide battery out and replace with new CR2032 3 volt Lithium Coin Cell Changing Pressure Units: While the gauge is on hold the ON button until the display start flashing. Then while the display is flashing press and release the ON button to select the desired unit of measure. Once selected wait until flashing stops to use gauge.