The 20PV-5P20 Pressure and Vacuum Swichgage is a 2" dual-scale dial, diaphragm-actuated, pressure-indicating and vacuum-indicating gage, with an adjustable pressure range of 0-30 psi, and an adjustable vacuum range of 0-20 inches of Hg/kPa. This gauge has built-in electrical switches used for tripping alarms and/or shutdown devices.