Capable of sensing very low positive or negative pressures, reliability and long life are inherent advantages of this design. Extremely easy set point adjustment: 1) Loosen the lock ring, 2) Turn interface either left or right until pointer is at the desire pressure or vacuum on range label, 3) Retighten the lock ring, and 4) Verify the adjustment by applying pressure or vacuum. See Switch Accessories at omega.com for Audible Alarms and Relay Modules.