The OD on the Dunhills of old stood for "own design", but let's admit it, for all intents and purposes we have used it as a size designation. I have never seen a small OD. That out of the way, the third letter (A,B,C, etc) was not an additional increase in size, but in quality. Could an ODB be larger than an ODA? Sure, but that isn't what the nomenclature was designed to communicate. This Dunhill ODB came back with Dunhill's resurrection in 1999, is a marvelous Bulldog-moving-to-saucer, and the elongated diamond shank and stem is simply perfect.
--R. 'Bear' Graves