Say propeller Tighten pressure and vacuum switches Pirate Several spade
Vacuum System Pressure Control Switch Pump Regulator Attenuator:Full Range from Upto 29 inch Hg, Adjustable Range and Span Differential Pressure: Amazon.com: Industrial & Scientific
Pressure & Vacuum Switches - SOR Controls Group
Vacuum Switch
Vacuum Switch - Eurovacuum
Vacuum Switches for Vacuum Pumps | Airpower
electronic vacuum switch, $ 94.70
LF08-V Vacuum Pressure Switch
Adjustable Vacuum Pressure Switch: Auto On/Off At Set Point - 2L Inc.