This is a pair of safety caps. These are made in the USA by Accu-Pressure and are designed to monitor the air pressure in your tires. They replace the caps on the valve stems on your tires and change colors depending on the pressure in the tire. A green cap means that the pressure is OK. A yellow cap means that the pressure is approximately 4 PSI low. And a red cap means that the pressure is at least 10 PSI low. These are available in 6 different pressure ratings. Make sure that you order the correct set for your application. Most people agree that most Goldwing 1500 and 1800 tires should be run at approximately 40 PSI. Allowing the pressure to drop causes poor fuel economy, poor handling, faster tire wear and unsafe riding conditions.