SMD VM-1 HV Analog LED DC Volt Meter (14-18v Systems) Input Range: 6v-30v - Constant LED current and brightness regardless of battery voltage (wont dim with your beat) Voltage Reading Range: 12.6v - 20.2v (Designed for 14-18v systems) Accuracy: +/- 0.20 Volts (due to the nature of a bar graph) 100% Analog circuitry allows for near instantaneous voltage accuracy versus a traditional digital voltage meter Response time from one end of range to the other is less than 130 milliseconds.