Bailey & Mackey’s range of Pressure Switches is built to the highest standards of workmanship required for such precision devices. Measure Pressures Relative to Atmospheric Pressure and are Divided into Three Main Groups, Each Group Being Based On A Different Measuring Principle. The Majority of Bailey & Mackey Pressure Switches Have A SPDT Micro-Switch Fitted, But Where Double Pole Switching Is Required, Bailey & Mackey Can Supply A Range Of Pressure Switches Fitted with A DPDT Micro-Switch.