Just for the record, I used to say the exact same thing!
I thought the HP-BH was the same as a HP-B, but with a MAC valve hanging off the bottom. It isn't. It is a larger bodied brush, with very few parts common between the two models. I REALLY like the way the HP-BH works, and it moved it's way right up to the front of the line on brushes that I reach for when starting a project. I have since put my beloved HP-B+ in the display case... even though I do have a Grex MAC valve on my air hose
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