The geared, solid brass precision movement is exceptionally accurate and unaffected by changes in temperature, humidity or altitude. We have also used this same gauge for over 20 years on everything from aircraft and company vehicles to bicycles and golf carts. The 12 inch flexible extension hose facilitates easy readings. A special bleeder valve releases excess air from the tire while monitoring tire pressure. The heavy steel case has a 2 inch diameter dial with an unbreakable crystal. The entire gauge is encased in a rubber, shock-absorbing cover to protect it if dropped. Gauges are calibrated in easy to read 1 lb. graduations.