Just got done restoring one of these and I am interested in finding more info on them. I have read they made them from about 1909-1929. This seems like a later model, based on the plastic handle material; feels like Delrin. I read they used Maganese in the steel for some reason? I did notice that it seems much harder than my other straight razors. I also noticed the "Reg. U.S. Pat. Off." on the tang and wonder what's up with that. Is there something special about these models that they patented? As far as I know about manganese's role in cutlery metallurgy, it can help grain structure and hardenability, but I am guessing with the patent mention that its more akin to some kind of gimmick like "magnetic" steels.