I contacted HPE directly - they said for that information I'd have to contact a HPE partner! WTF - HP doesn't even know its own part numbers? So I contacted two partners and neither knew what the part number was!
I can't believe it is this hard to find a part number for the MSA 1050 or perhaps my client is the first sucker to actually buy HPE crap. I would NEVER EVER EVER EVER buy HPE junk again after this experience - part isn't in their manua, part isn't available from HPE and their partners can't get it either.
I knew HP was a challenge to work with a decade ago (the last time I had a client with HP servers) and I see they've gotten even more difficult to work with over time.