Vintage Minerva Rare Chronograph Bi-Compax, Stepped case, Shrouded Lugs, Cal. 13-20 Swiss MadeThis rare vintage Minerva Bi Compax Chronograph houses the legendary Calibre 13 20, a movement of enormous historical significance. First introduced in 1923 in collaboration with Dubois Depraz, this was one of the earliest dedicated wristwatch chronograph movements. While originally a mono pusher design, it evolved into the dual pusher format seen here by the early 1940s, offered in both 30 and 45 minute variants. The Minerva Cal. 13 20 was used in