No more expensive, heavy, voltmeters in your airplane!. Small size weighs 4/10 of an ounce and draws only 3/10 of a milli-amp with 8 to 19.99 volts. Smaller size may be permanently attached to an aircraft’s electrical system, without fear of draining the battery. System voltage monitor, 8 to 19.99 volts. No backlight. Power source: from the system, 8 to 19.99 volts. 300 micro amps nominal. Recommended for continuous power monitoring.