This Assured Automation 2 wire single reed switch can be used with the WM-PC and WM-NLC mechanical water meters. When coupled with a digital pulse reader (like KAL-D06 or T210), it's helpful when it's difficult or impossible to read usage results where the meter is physically installed (in a ceiling, crawl space, pit, renter's home, etc.). The switch comes in a length of approximately 5' and has an approximate life of 1 million pulses. You can extend this length by using additonal Thermastat wire. Installation into the meter is completed by simply screwing the switch into the face of the meter.