The Xtreme Ballasts feature extruded aluminum casing to provide cool operation. They have a vibration dampening system for noise reduction. They are very quiet. It can be run at 120 or 240 volts. No rewiring is necessary. They will all run either M.H. or H.P.S. bulbs (with the exception of 600w which will run H.P.S. bulbs only.) They come with a 120 volt power cord.