Monitor the charge of your stored 12 V motorsport lead acid battery or check if the vehicle charging system is working correctly 2 automatic modes - battery state of charge monitor (single LED flashing) and charging system test (arrow mode) 4 LEDs cover the voltage range æfull to emptyÆ voltage range of all 12 V batteries, including higher voltage AGM for power sport (4th vv LED = 12.7 V) Battery charge level : LED matching charge level blinks every 5 seconds (long term draw less than 0.2mA) Vehicle Charge system : LED arrow mode activates when charge voltage reaches minimum 13.5V (v green LED) or ideal range of 14V+ (vv green LED) High quality battery monitor, designed by TecMate. CORD W/TEST LEAD JAR 20