it looks like a PFO 400w X2 ballast.
PFO isnt in business anymore, but the MH ballasts that they made are fantastic. they are mag ballasts and last forever.
what kind of information are you needing?
for 55$, and if both work, then its a good deal. but you have to think. its a dual 400w ballasts, so thats a lot of electricity. plus its MAG and not electronic. so it will overdrive your bulbs which is a good and bad thing. it gives better PAR, but you wont get more than 12months out of a bulb if that depending on the bulb brand.
they MAG ballast are larger for heat distribution.