Ceramic metal – halide, or CMH for short (some call it CDM), is becoming increasingly popular in the gardening industry. CMH lamps have a very wide light spectrum, which is closer to the sun than any other form of HID lamp. CMH lamps also have increased AR / Watt efficiency compared to other forms of HID lighting. The CMH device can be used as a main light; main light for SOG applications; or additional full-spectrum light for large harvests. The CMH 315 horizontal mounting location on a single lamp ensures even light distribution. Can be used with any 315W 3000K or 4000K CMH lamps.