The AEM Volt Gauge has a bright LED display that shows voltage in .1 increments, and a sweeping LED "needle" that lines the edge and changes color as voltage changes from 8 to 18V. Most charging systems will slowly start to decrease their output, so you will be driving with a failing system before the light on the dash comes on. With a real voltage gauge you'll know there's a problem before you go to start the car - or worse - get stranded on the track on away from home. 

Each gauge includes interchangable silver and black bezels and black and white faceplates to personalize the look of your gauge - it's like having 4 gauges in 1!