BREITLING PLUTON CHAPTER RING

  • I'm thinking of buying a vintage Breitling New Pluton as companion to by Chronosport UDT type II. Most have a curious range of numbers in alternating colors on the chapter ring. '35' at 3 minutes, '50' at 6 minutes, '75' at 9 minutes, etc. I know they aren't points of the compass. But believe they have something to do with visual and instrument flight rules - allowed altitudes for flying. Breitling is known for use by pilots, so this makes sense. But I see this same chapter ring on their dive watches as well. Anyone have more information.