Material: Chrome metal and PC size: 1 cm x 2.5 cm. Visually warns you when tire pressure is low. Helps prevent premature wear of underinflated tires, increases fuel efficiency, safety and control, extends tire life. Green or Yellow or Red system indicates the correct tire inflation level. According to the color recognized to display tire pressure, green indicates that the tire pressure is normal. Yellow indicates that the pressure is 10 percent lower than the standard. Red warns you that the pressure is 25 percent lower than the standard. 36 psi (2.4 bar), applicable to car, motorcycle, bicycle and so on. Warning: When removing the cap, make sure you do not lose the black washer. They are prone to falling and are very difficult to find. It is advisable to remove them before your car is serviced in a garage. Package contents: 4 valve caps with pressure indicator. Warning: When removing the cap, make sure you do not lose the black washer. They are prone to falling and are very difficult to find. It is advisable to remove them before your car is serviced in a garage. Material: Chrome metal and PC. Round style 36 psi. Valves indicating low tire pressure to prevent wear or punctures of underinflated tires. Improves road grip, more economical, extended tire life. p> Green or yellow or red indicator shows whether tires are properly inflated. Saves fuel, improves safety and control. Recommended pressure: 32 psi. Simply attach the tester to the tire air valve. Indication: The green light indicates that the tire pressure is normal. The yellow light indicates low tire pressure (approximately - 2.2 kg). The red light indicates very low tire pressure (approximately - 4.5 kg) . Installation: Determine the appropriate pressure for your tires. Inflate the tire to correct the pressure. Securely secure this new pressure cap. Just look at the color to know whether your tire is inflated enough or not. Package included: 4 x valve caps with pressure indicator .