You can find many experts past and present on Rolleiflex cameras but the three that come to the top are Claus Prochnow, Ian Parker, and Arthur G Evans. All three meticulously researched the Franke & Heidecke and Rollei-Werke archives but came away with different priorities and styles when naming many cameras. The Rolleiflex T for instance, all three agree that they are Rolleiflex T cameras and two out of the three agree on the number that follows the T for each camera. It then comes down to style and when Prochnow uses “model” Evans uses “type” and Parker just uses a number. The camera pictured here is a Rolleiflex T (Prochnow “model 3”) (Parker “2”) (Evans “type 3”). This T model serial numbers went from 2242000 to 2249999. The Rolleiflex T was produced from 1958 to 1975. It is a 120 film TLR (twin-lens reflex) camera with a Carl Zeiss Tessar f3.5 75mm taking lens with a Synchro-Compur X or MX shutter and a Heidosmat f2.8 75mm viewing lens. The T model came in a few iterations and in the end of production some came with a Schneider Kreuznach Xenar f3.5 75mm taking lens, the same as the Rolleicord (about 3,000 units). If you go by serial numbers issued for the camera, the count of numbers used to produce the Rolleiflex T comes to 260,643 in all its forms. Wiki tops out the number produced at about 120,000.