Longines ultrasonic started to use the Accutron (bulova) machine, which was not available in many watches in the 1970s. 37mm case excluding crown is available. The diameter from handle to handle is 44mm. The glass is original, has not been replaced and is as clean as the first day. glass toughened mica. The dial is original sunburts dial. very special number part. When viewed sideways, it seems out of this world. It is a very enjoyable model. A must have for collectors. It has a brown colored genuine leather strap. Even though 55 years have passed, there are hairline scratches on the case, almost as clean as the first day. Anyone who wishes can have it polished. But it's better to keep it original. I have been in the store industry since 2003. I love wearing and selling watches. I offer you the best and cleanest watches. After determining its originality, I have all the maintenance done. It makes me happy that everyone is happy