Got mine. These are nicer built than the original China made one I had and drew up in Fusion 360. A little different for the mounting, but basically the same, but better quality. The divisions are not as marked though.... not 0.0005" per division as marked. The screw is the same as my original one and is 7/16" - 20 threads so it's 0.05" per revolution, so it's 0.001" per division, so 0.002" on diameter.
Maybe this is why they were so cheap??? Mismarked??? Check the price for these BHC2 heads at MSC. Hundreds of dollars for a head, a couple of bars and a box!!! These are made in Taiwan and not China BTW.
Glad I got two!
Ted