Operate off of 12V external power supply (machine battery/charging system). Feature digital numerical readout, as well as a bar graph display. Waterproof, rugged design. Easy-to-read, clear vivid display. Large buttons make changing functions easy, even when wearing gloves. Feature a convenient clock. Internal memory records peak readout. Tachometer features adjustable sensitivity and updates every 0.3-0.6 seconds, with a range of 0-19,999 rpm. Gauge body measures 78mm L x 40mm W x 20mm H.