GAUGE, VAC/BOOST, 2 1/16", 30INHG-20PSI, MECHANICAL, MARINE CHROMEThe Standard In The Industry, Autometers Mechanical Boost Vac Gauges Have Found Their Way Into More Builds Than Any Other. Using A Patented, High Precision Bourdon Tube Meter Movement, There Isnt Another Gauge On The Market That Can Lay Claim To The Levels Of Accuracy Or Durability You" Ll Find Here. A Simple 1 8" Npt Pressure Connection Requires No Electrical Hookup For Operation. Appropriate 1 8" Npt Fittings And Line Kits Are Available Separately.