iSaddle New Car Tire Pressure Monitor Valve Cap w/Sensor Indicator 3 Color Eye Alert 4Pcs Material: Chromed Metal Round Style: 36PSI Visually alerts you when the tire pressure is low to help avoid premature tire wear or blowouts from under-inflated tires Enhances road handling, increases economy, extends tire life Green/yellow/red system indicates level of proper tire inflation Increases fuel efficiency, safety and control For use on 32 pound per square inch recommended pressure Simply install on the air valve Indication: Green shows that tire pressure is normal Yellow shows that the pressure is down about 5 pounds Red alerts you that the pressure is down by at least 10 pounds Package : 4 x Tire Pressure Indicator Valve Stem Caps