Hydro Crunch 600W HPS MH Digital Dimmable Ballast for Grow Lights
Spectromaster Dimerabile Digital Ballast 600W Spectromaster 600w Digital Ballast | Products \ Power Supplies Products \ Power Supplies | Maxgrowshop.com
TOPHORT 600 Watts Digital Dimmable Electronic Ballast for HPS MH Grow Light Bulb Lamp (600W, Blue)
Lux Plus 600W ballast / Very efficient and affordable
Horticulture 600w Dimmable Digital Electronic Ballast With 600w HPS Bulb | eBay