I should probably also add - some of these very inexpensive heads have really poor QC, which is hardly unexpected. The sellers selling them are also all too happy to start selling silent revisions or perhaps just similar looking products.
For example, I bought a Muhle R41-like head from one seller which was somewhat different from the original (tabs covered, blade clamped near the cutting edge), liked it enough that I wanted another one and what arrived was a much closer R41 copy.
There are heads looking like Yaqi's Knight Helmet heads floating around on there as well, but the one I got had much worse plating then the Yaqi and retainer pin and hole position was a little different, too.