Auto Addict Air Alert Tire Valve Cap - Set of 4Pcs. Instructions: 1. Description 100% brand new and high quality Material: Chromed Metal Simply install on the air valve According the recognize color to display the pressure of the tire Fit on any standard size existing tire valve stem Visually alerts you when the tire pressure is low to help avoid premature tire wear or blowouts from under-inflated tires Sing it makes the tire of your car more safety Easy to control and install Tire Pressure: Color: Silver .Size Approx. 2.3 x 1cm/ 0.91" x 0.39" (L*D) 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 Installation: Determine the correct tire pressure for your tires Inflate tire to correct pressure Install this new pressure cap tight Simply look at the color to know if your tire is low or normal.