Just when I thought that Group A was the beginning of production, Dave France came along with an earlier brace, marked: "PAT NOV. 6 23" over "OTHERS PENDING."  That first patent was for the general concept of the brace.  It is conceivable that there may be a "YANKEE" 2100 brace out there somewhere marked only Patents Pending.  The latest the present brace could have been made is January 13, 1925, the date that the second patent was granted.  That's slightly more than one year of production.  Rare, indeed !  In all respects, this brace otherwise resembles the Group A braces (two patent dates, others pending) most closely, especially with respect to the pad, its ball bearing housing, and its metal plate.  It's marked "2100-10 IN" on the bow.  This one isn't for sale.