MBSAW-500 is an introductory non-monitored Air-Wave sensing edge. When the sensing edge comes into contact with an obstruction, an air pressure wave is pushed through the internal hose to an external Air-Wave switch (sold separately). The diaphramgm inside the switch then activates an electrical contact, which sends a signal to operator controls to stop and/or reverse door operation. The top tab inserts between the double-L angle bottoms bars on a rolling door.