440G-LZS21SPRH is a type of guard master control relay made by Rockwell Automation. It is a safety relay that can be used to monitor a variety of safety inputs and to automatically shut down equipment when required. This relay can be connected to up to 2 safety devices, such as emergency stop buttons or limit switches, and can detect if one of them has been operated. The relay has a built-in status indicator that can easily help in diagnosing a potential issue, such as an open disk or a blocked system. It can be used with a variety of inputs, including AC, DC, or 24V DC, and is available in either a plugging or an open-style housing.