Our 600W HPS Ballast(s) are a great selection of over 16 units that offer your indoor garden the red color it needs for the flowering stage of your harvest. We have many manufacturers such as Sun System, Galaxy, and Lumatek. These also come in Magnetic, and Electronic. One of the great benefits of some of the electronic ballasts is the fact that they can switch wattages and voltage. The other benefit is that they do it automically without you having to switch a button or change a plug. We are very proud of our selection and would be more than happy to give you support if you need to speak to one of our professionals our number is (888) 606-2149.