Unknown Darby Collar

A collar, based on the "Darby" lock mechanism, I.e. a screw-bolt. Unlike most Darby's, the bolt is NOT spring loaded. The key is also somewhat different in that it has a square hole in it rather than threading. It is inserted into the lock mechanism and on to the receiving peg at the end of the bolt which is similarily shaped. Turning it clockwise locks the collar by screwing the bolt INTO a hole in the bow. Turning it counter-clockwise unlocks the collar by removing the bolt from the bow.