. The Galaxy® Grow Amp® 600 Watt ballast can operate a 600 watt lamp at 400 watts & Turbo Charge® a 600 watt lamp. These ballasts will properly drive 400 Watt HPS/MH, & 600 watt HPS lamps or properly drive 400 Watt HPS/MH. Set the desired wattage on the Select-A-Watt® dial & install the correct lamp. Galaxy® Grow Amp® ballasts come pre-wired with a Sun System® lamp cord receptacle. They are compatible with all Sun System® branded reflectors. Includes a 6 foot 120 volt power cord. Purchase a 240 volt power cord separately (#903088). Specifications: extremely efficient - 99.9%; 902215 - operates 400 watt HPS/MH & 600 HPS lamps, 902235 operates 600 HPS and 750 HPS/MH lamps, 902220 operates 400, 600 and 1000 HPS/MH lamps, soft starting, extruded aluminum housing, fan cooled for superior thermal management, lightweight, very quiet and limited vibration, voltage: 120 or 240, Part No. 902220 and 902225 are compatible with double ended lamps. 902225 is 240 volt only.