I agree. This is a Revonoc brand holster from Hibbard, Spencer, Bartlett & Co. I haven't seen too many of their holsters, but they've all been marked on the back. Perhaps yours is a home-made Revonoc-off?The flap is what sets this holster apart from what was, at one time, a fairly popular back pocket or overcoat pocket holster. Most were of rectangular shape (to match the pocket shape) with an open top. The two slits in yours would have been added later, of course, by someone who wanted to wear it on a belt.