Hobbs Switch. Boost Activated, Boost Level Adjustable. Commonly used for automatically turning on secondary items such as additional injectors, intercooler misters, water injector, nitrous. The popular boost sensitive “hobbs” switch features 1 wire switching to turn on secondary devices such as additional injectors, intercooler misters, water/alcohol injection, or nitrous. The unit has two additional unique features: 1) Standard 1/8NPT style pressure port for universal use. 2) Boost trigger level adjust (4-25 psi) via the top allen screw. this item is now only available in fixed setting, please contact us for more: 10 PSI Pressure Switch 15 PSI Pressure Switch 35 PSI Pressure Switch 60 PSI Pressure Switch 100 PSI Pressure Switch Switches operate with either ascending or descending pressure by choosing normally open or closed terminals.