Digital is a new long lasting low electricy use type of ballast.It what most places sell now versus the old big heavy ones.They allow you to overclock your lights so a 95000 lumne lamp will give almost 300 % more light and they use about 30% less electric to run which means cost less to use them.They also run cool so they dont add heat to a grow area and they are auto start no waiting for long warm ups.I grabbed 2 600 watt digital from that web site and love them. I paired them with 95000 lumnes of enhanced spectrum bulbs then with the 30% extra from my bulbs have massive 247000 lumnes coming out and only using about the same energy as 800 watts of electric meaning more light then 1000 watt setup more coverage less heat and less electric cost.I got a light mover made a homemade almuinum cross bar and it moves both lights for me.