It turns out that two of my major desires, turned acquisitions have something very much in common. Both watches contain a movement that was initially designed for pocket watches. As a result, both the Zenith Montre d'Aeronef Type 20 Special and the IWC Ref 5251 both had to be relatively large to accommodate the movement, the Zenith clocking in at 57.5mm, and the IWC at 46mm. Both movements have exquisite finishing. Unfortunately my IWC is one of those rare closed back versions, this one dating to 1982, so I cannot show the breathtaking beautiful caliber 9521 heart that beats within.