This is an Enphase IQ combiner 3ES. It combines circuitry and breakers for combining the output of multiple solar collectors/arrays, monitoring production using the integrated Envoy controller, and connecting to your main load center (breaker panel). It is designed for IQ -6/7 and IQ-8 microinverter systems. It will also work with M215 microinverters but would need a COMMS-KIT-02 addon. It was used for 2 years before I upgraded my whole system. Works perfectly, includes two 220V breakers (1 x 20 and 1 x 15). Cost when new is $780.