93% japanning. 1895 and 1910 patent dates behind the frog. 2 3/8 inch V logo iron.. These "flat top" Bedrocks are highly sought after by users. They have the triple screw frog design, which allows you to adjust the frog while the iron is set, allowing you to tighten the mouth with utter precision. Bedrocks also have a frog that mates completely with the edge of the mouth, for a much more solid assembly. This eliminates chatter. Thus, the name "Bedrock."