i managed to score this auto strop in a lot of razors last week. the only other one ive seens handle is rounded at the bottom and has a late 1920s head. this handle is the earlier flat bottom knurled variety, and the head is the first (not counting the prototypes). the SN puts it around 1913.
i put a normal size valet next to it for size comparison. from what ive HEARD theres only 5 known, but i cant be positive of that.