Mitchell Aircraft Products, Inc. Gauges are American manufactured to exceed TSO specifications yet are affordable for home-built aircraft. Selected models are PMA approved. All gauges fit standard 2 1/4" holes and have a full 2 year factory waranty. Gauges are standard 12 volt operation and include internal lighting. 24 volt operation only requires a small ballast resistor. Call for special range marks available, at additional cost.