The Blue Sea AC Digital Frequency measures frequency on your marine equipment in large (9/16"H) LED characters that are easy to read in low light, at angles, and from a distance. Calibrated with sine wave input. Features three levels of brightness and a splashproof front. Manual sleep mode conserves power. Easy spin-on mounting system for simple surface mounting with a 2" diameter hole or panel mounting with removable bezel. • Input Voltage: 80-249V AC• Power Consumption: 0.6 Watt minimum; 1.0 Watt maximum• Accuracy: ±0.1%• Dimensions: 2.9"W x 2.43"H x 3.4"D 3 levels of display brightness Manual sleep mode for power consumption | Blue Sea Systems AC Digital Frequency Meter, 40-90Hz