The FMM (Fluid Monitoring Module) is a module that connects to any Apex (Apex(2016), Apex Classic, Apex Lite, Apex Jr.) via its AquaBus port, providing four multifunctional ports for flow, water-level, and leak detection sensors. Each port can accommodate different types of sensors to create a custom monitoring setup. Plug in a flow sensor for your return pump, an optical sensor for sump level detection, and two leak detection probes - no problem! The FMM will automatically detect the type of sensor connected.