Time to trim down the collection a bit so for sale is my Omega Speedsonic. Reference: 188.0001. Omega cal. 1255. This movement is pretty unique: it is based on the 300Hz Esa caliber 9210. Although this watch is a derivative of the Esa 9162, its uniqueness justifies looking at it more closely. The 9210 is the only tuning fork chronograph ever made. It was also used in Longines Ultronic and Certina chronographs and probably others as well. The chronograph mechanism is in modular form (refer to the Esa 9162 and 9164), and mounts on the dial side of the movement. Being of a Vertical Clutch design, it doesn't suffer from the inaccurate start/stop problems of standard sliding-clutch chronographs, It contains the gear train for the chrono mechanism, the chrono mechanism itself, and a train for driving the hands and date mechanism. Also, it has the day and date functions built into it, as well as the time and chrono functions. Case diameter 44m excl crown. The dial is really mirrorlike: see pictures. Recent –very expensive- service by a watchmaker with an Omega parts account so everything works as it should. Both daywheel and datewheel have been replaced by NOS ones. Please remember this when comparing prices . Original Omega 1162 bracelet. Asking: EUR 1.750. I live in the Netherlands and have dozens of references. Paypal or bank. Shipping at cost. No trades please.