Re: Metal Halide bulb question.
WTA, the buld you pictured is a 400 not a 600MH but you probably knew that. Also something to consider which is good in this case is that the " U" at the end of MH 400/U means it is universal meaning it can be used in a horizontal or vertical fixture. Some are made to only be used in one or the other position and will indicate that as well. I'm with Sandy that if he isn't giving it away super cheap just go get a new one. As a spare though......great idea. Now that I think of it I should get a couple of new ones at this point and keep the current 2 I'm using as spares.