I've seen a lot of Universal Geneve chronograph's. I've never seen one this small or with this caliber. 25mm! What caliber is it? I love it. http://www.liveauctioneers.com/item/5466143
The auction listing says it's a cailber 289, a 10.5 ligne movement. That's extremely small for a chronograph movement. You're talking 26mm to 27mm in a round case. It's not shown in Ranfft, but I was able to find a very rare square Uni-Compax that uses the same movement: http://www.chrono24.com/en/universa...ph-18k-yellow-gold-1940s-12105--id2535439.htm Hope this helps, gatorcpa