Aluminum casings, sealed lenses UV protected needles for fade resistance Non-corrosive hardware Come with White Lights with Red removable cover 3 7/8 Outer diameter 3 3/8 hole size Require the use of a pitot style water pressure feed system for operation**Pitot pick-ups sold separately. New Autometer Pitot Operated Speedometers do not include a fitting. See related items below for Pitot hose fittings.