19th century Germany Frog & Adjuster based on F.X Tourte model.
The milling on the screw is that of Tourte. The throat on the frog that of Tourte. The upper and lower talons is that of Tourte, too.
Three pins on the lower talon and two pins on the upper talon is what you can expect to find on Tourte frogs, which in turn was copied by Nicolas Kittel. So is this the work of Carl Heinrich Knopf?
Tarisio estimate range is 4k to 6k USD. Tarisio Reserve price: 2000 USD.
Currently the frog assembly is with Tarisio. Call Ben Gagnon at Tarisio NY and buy it from Tarisio directly now if you wish.