The Bezel is a tachyameter. It shows the speed of an object. In this case it starts after half a minute, which means, that if for instance a car drives one kilometer in half a minute that is equivalent to 120 km/h. If it takes the car one hole minute to drive the kilometer it has run with a speed of 60 kilometers/hour an so on. The unusual thing is that this bezel doesn´t operate with a speed higher than 120 km/ h, but that might be because the watch is meant to measure the speed og sailing vehicles, that seldom reach a speed higher than 120 km/h. It is lovely watch, which I happen to own myself, but mine has a normal bezel.
Best regards Lasse