Hi, thanks for your reply. This telemetric bezel is graduated to indicate the speed in air. It allows the user to calculate the distance between the observer and a situation that is observable both visually and audibly. It was mainly used for military purpose and weather situations. For more details please see Chronomaddox.com/4bezels.
My watch was delivered to RCAF in july 1966, so probably for military use. Best regards !
Click to expand...