Yep, it is a MH ballast with a HPS igniter on it, but your MH bulb will lose some hours working with the igniter. Also, that link I posted on how to wire your ballast has instructions on a double room relay I believe. These things can get pretty hot, I am about to put a pan under the 400w because I have it going 24-7 right now and the thing is extremely hot to the touch.
Brook if you stop in here, miss you.
Adieu