A perfect match to Kuryakyn 's flush-mount gas caps. Replaces the difficult to read stock fuel gauge. Sleek, low-profile design. Incorporates both a LED fuel gauge and a LED battery gauge. Color-coded LEDs make them readable at a glance from the seat. Replacement stock fuel gauge on 94-21 Road King; 00-17 Softail; 91-17 Dyna; 88-94 FXR.. A daylight sensor automatically adjusts the brightness of the LEDs. LED lights are bright during the day and dim at night. The fuel gauge has a string of color-coded LEDs to indicate fuel level. The battery gauge is an array of LEDs that indicate the operating voltage of the bike's electrical system. Various color-coded LEDs indicate safe operating range, bike is not charging or impending stall.