Two basic variations of the IIa/IIIa were made: the so-called "black dial" and "color dial" cameras. The black dial cameras used a special flash synch cord for either flash bulbs (1361) or strobe flash (1366). On the color dial cameras the ability to use the flash bulbs was eliminated; a P/C connector was added, and strobe synchronization was the only option. Where the Leicas of the day had only electronic flash synch at 1/25s second shutter speed, the Contax IIa/IIIa was synched at 1/50s and all slower speeds. Further, with the adjustment on the 1365 flash cable used with the Black Dial camera, the user could tune the flash to the individual shutter, and synch strobe to the 1/100s! At the time, this sort of shutter speed with a strobe was unheard of, and was a major technological feat. On the later color dial cameras, the 1/50s marking on the shutter speed dial was painted chromate yellow, while the speeds of T, B, 1, 2, 5, 10, and 25 were black, and 100, 250, 500, and 1250 red.