Calibrated in 1/2-volt increments with 9 color-coded LEDs, you can instantly tell the state of your electrical system without taking your eyes off the road for longer than glance. With a range between 8 and 16 volts, green LEDs in the 12.5 to 14.5 zone show a safe charging range for the circuit the gauge is reading. Yellow LEDs on either side warn of over- or under-charging, and red LEDs at the extreme ends flash to indicate an impending electrical system failure. A built-in daylight sensor autimatically adjusts the brightness of the LEDs for day or night operation. An essential item for heavily farkelized machines, or any bike with a low-output alternator. Measures 1-9/16 x 1 x 1/2 inches.