The Venus 210 family was a cam-switching chronograph design. Closely related to the Venus 188 family, it reduced the diameter of the movement to 12.5 ligne. The most notable member of the 2-member movement family was the Venus Cal. 211 with its dual-disc big date window at 6:00.
More detail on the history of Vénus is available in the Grail Watch article, “The Rise of Vénus, Legendary Chronograph Maker“