The Model BPMS-1 Speed Switch is used for accurate sensing of Under Speed, Over Speed and Zero Speed conditions on rotating shafts, pulleys or other rotating equipment within your plant. It has one of the most innovative designs for installation today. It utilizes a magnet for attachment to the rotating shaft. Tapping the pulley and coupling the speed sensor is no longer required. Simply apply the speed sensor to the shaft and a strong magnet holds it in place, wire it up and you are ready to go.