Milliard 600W Digital Dimmable Electronic Grow Light Ballast - Compatible With HPS and MH Bulbs - ETL Certified Great start to any indoor garden setup. Mounts vertically or horizontally with built-in mounting flanges. Quick lamp ignition to light up bulbs 1-2 minutes max. Automatic frequency adjustment for MH or HPS bulbs and stable light output by constant lamp voltage for flicker free lamps. Variable output setting for 250, 400, or 600-Watt bulbs. Super Lumens setting boosts output by 10% to extend the service life of exhausted bulbs. Operates on 110-120 Volt or 230-240 Volt input. Built-in fuse for overload protection. 6-foot power cord included. Dual cooling fans, aluminum body, and forged heatsink fins for efficient heat dispersion and minimizes ballast temperature. ETL Certified