The Metered NI-STARTER has a durable, shock resistant, dual faced amp meter to show the condition of your glow plug. When attached to your glow plug the meter will indicate plug condition, good or failed. This aids in determining the cause of many starting problems. The meter does not indicate the NI-STARTER charge condition. All versions of the NI-STARTER carry a 180 day warranty against defects in workmanship or the materials used.