... alerts the driver by a blinking LED whenever the tire pressure falls 5-7psi below the original pressure3.reduce tire wear ... CO2 pollution4.installation: just tighten the low tire pressure alert cap onto valve stem bu finger,no tool required.5.the alert ... it: Car, Van,Trailer,Bus,Truck,Motorcycle,Bicycle The tire pressure warning cap support all tire pressures between 20psi and 130psi ...