1)Quality Gauge Used on air, steam, 2)oil, fresh 3)salt water Quality Gauge Specifications Dial3.5"(90mm),4.5"(115mm),6"(150mm CaseBlack Plated Steel/Black Plated Alu. LensGlass RingBrass or stainless steel InternalBrass or stainless steel ConnectionBrass or stainless steel,1/2" or 1/4" NPT Range30"Hg.Vac./kpa -- 0-5000 Psi/Kpa Accuracy±1% or ±0.8% Quality Gauge