Philips GreenPower Plus 600 Watt EL lamp is one of the best 600 watt HPS lamps on the market. Specifically designed for high frequency electronic ballasts it has a connection at each side of the lamp, removing the need for a frame wire inside the lamp. The absence of a frame wire eliminates any shadows in the beam. Instead of being vacuumed it is gas filled, which allows for a smaller arc tube, improving the optical control. HPS 600w 400v Philips Master Greenpower EL 39 (EL-special designed for electronics) Only use on commercial grade 400v Gavita systems!!! Highest Micromole output in the industry. Brand: Philips Type: Master GreenPower TD EL 600 E39 Power: 600 Watt Voltage: 400