1) Ammonia Gauge Used to display pressure and temperature 2) on closed refrigeration system Ammonia Gauge Specifications Dial2.5"(50mm),4"(100mm),6"(160mm) CaseStainless steel / Black Paintied Steel LensPolycarbonate RingStainless steel / Black Paintied Steel InternalStainless steel / Painted steel Connection 1/4" NPT Range30-0-150 PSI/F, 30-0-300 PSI/F Accuracy±1.0%,±1.5%,±3-2-3% manometer ...