The FA-CS1M Off-Camera Shoe from Sony attaches to an
external flash equipped with the multi-interface shoe, and connects it
to Sony's wired off-camera eTTL flash control system introduced by
Minolta. This wired system provides off-camera eTTL exposure control of
flash units in cases where the wireless system can't be used. The
FA-CS1M gives you the 4-pin port that accepts the system's wired
connector. Any external flash with the multi-interface shoe that doesn't
already have this 4-pin port is compatible. The required 4-pin
connector cables FA-CC1AM, FA-CS1AM and FA-EC1AM are available
separately.