You haven't mentioned TTL, but I'll address it too.
The 555 has modules for different cameras for dedicated and TTL operation, and a non-dedicated, non-TTL module also. They connect to the flash with a cord, so they can stay with the camera as the flash is moved around. The modules also have their own sensor; on TTL cameras the flash can be set to "A" to use the module's sensor when the module is connected to it, or the blue dot for TTL (there's also "M" for manual, of course). On non-TTL cameras, the module will act as a remote sensor when the flash is set to "A".
The universal, non-dedicated, non-TTL module is STD-1D. Modules do not connect directly to the 555. The EXT-11 cord is necessary, and allows off-camera flash. It's coiled, and can extend to about 3 feet.
I have the Bronica sensor, which has no contacts on the module's foot, as the separate TTL cord connects to the body. I suppose, but don't know, that any module with hot-shoe contacts on its foot would be able to trigger and control the flash on the flash's "A" setting.