EFORCAR Auto Car Tire Tyre Wheel Air Pressure Monitor Valve Stem Caps with Sensor Indicators Alert Chromed Metal,Fit for cars,bikes and motos-4PCS/SET 2.2 BAR 32 PSI Easy to hanle,what you need do is just to replace the original valve cap.Easy to install,no need any power supply/ battery etc. Chromed metal round style,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. It not only saves the trouble of checking the tire pressure frequently,but also improves the safety of driving,so that you have a good sense of convenience,save worry and security. Whether it is the usual maintenance of the tire or the vehicle driving safety aspects have a considerable role! Applicable to car,motorcycle,bicycle and so on.