Cal. 11 was a two-pusher column wheel chronograph movement produced by Landeron in the 1940s.
Dr. Ranfft suggests that Cal. 11 is a monopusher, but other sources suggest two pushers. Given that Cal. 11 has six columns to Cal. 13‘s five, it is likely that this is a two-pusher movement rather than one. Ranfft also suggests that it is “like 13, but weaker main spring” and that it was produced in the 1930s and 1940s.