Striebel Eltron SOM 9 Plus (RESOL DeltaSolBX Plus) diffferential temperature control with digital temperature display, programmable functions for solar domestic hot water systems and 10 selectable systems layouts. 100-240 Volt operation. Control requires minimum 2 sensors (5 are included) and will accept up to 8 sensors. There are four semiconductor outputs and one relay output for pumps or valves and one output for VBUS data transfer. Equipped with a factory installed cord.