The L.E.D. Battery Gauge is an array of L.E.D.s indicating the operating voltage of the bike's electrical system. Green L.E.D.s represent normal operating range of the charging system, 12.5 to 14.5 volts. Amber L.E.D.s warn the rider that the bike is not charging. Red L.E.D.s will flash if the reading drops below 10 volts or exceeds 15 volts to alert the rider of an impending stall or the possibility of damage to the battery and/or sensitive electronic components on the motorcycle. Simple two-wire connection. Compact size (approximately 2" x 3/4" x 3/16") makes installation a breeze. A daylight sensor automatically adjusts the brightness of the L.E.D.s; they are bright during the day for visibility and dim at night. Universal fitment designed for all 12-volt charging systems. Note: Kuryakyn part number: 4218.