High Efficiency: With a total output of 1700 μmol/s and a wattage draw of 680 watts, the ROI-E680 has a 2.5 μmol/J system efficacy. So you save about 40% on electricity costs compared to HID. Additionally, lower heat output cuts cooling requirements by up to 40%.Provides Full Control: The onboard dimming function lets you adjust the light output down to 80%, 60%, or 40% when plants don’t need the full power, cutting down on your electricity costs.Even Light Distribution: Because of the large 8-bar design size, the light from the fixture travels