Autometer Carbon Fiber Series 2-1/16'' Boost/Vacuum 30 IN HG/20 PSI Gauge (4701)Carbon Fiber Series 2 1 16'' Boost Vacuum 30 IN HG 20 PSI Autometer Gauge The 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 youll find here. A simple 1 8 NPT pressure connection requires no electrical hookup for operation.