About this item ADD A CHECK VALVE - 28146 Vacuum Pump Switch keeps the pump from constantly running and preserves pump life. Vacuum pump After the pump is shut down, vacuum loss occurs. Simply put a check valve between the pump and the switch and your good to go. WORKING VACUUM RANGE - Our booster vacuum pump is designed to kick on when the vacuum falls below 0.04 MPa and kicks off around 0.06 MPa.This switch will turn the pump off or on at a preset amount of vacuum.It is a pressure automatic adjustment switch. PRESSURE SWITCH AUTOMATIC ADJUSTMENT - To prevent the screw from coming loose in transit, The adjustment screw of the switch has been glued with glue. This range is preset and cannot be adjusted.It will turn the pump off or on at a preset amount of vacuum. PERFECT FIT - 28146 Vacuum Pump Switch fit for our electric vacuum pump for brakes,Many customers also like to use it for AC Delco (Hella) vacuum pump and 79 Corvette,etc. IMPORTANT TIPS - At the connection, be sure to tighten, otherwise there will be leakage, which will affect the use of the pump.After the correct installation,it works exactly as it's supposed to.If you have any questions, please contact us, we provide warranty. › See more product details