Bourdon type mounted on brass pillar with nozzles for in and out connections 3/8" O.D. Heavy cast iron base for stability. Calibrated 0-30 inches of Hg / 0-750mm of Hg. Used for Vacuum Experiments. Bourdon type mounted on brass pillar with nozzles for in and out connections 3/8" O.D. Heavy cast iron base for stability. Calibrated 0-30 inches of Hg / 0-750mm of Hg. Used for Vacuum Experiments.