Car tire cap tire pressure monitoring cap air pressure detection gas cap Features: Fit on any standard size existing tire stem Visually alerts you when the tire pressure is low to help avoid premature tire wear or blowouts from under-inflated tires Material: Chromed Metal Round Style: 36PSI Size: approx. 23 x10mm 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 if your tire is low or normal Note: Please allow 1-5mm differences due to manual measurement. Included: 4pcs x Tire Pressure Indicator Stem Caps