The ARRI KC 155-S connects the EXT socket (Fischer 16 pin) on the ALEXA or ALEXA XT family of cameras to the EXT socket on another ALEXA and ALEXA XT camera in order to synchronize sensor readout and HD output clocks for 3D and other applications where precise synchronization of two cameras is needed. Can be used concurrently with the Ethernet to Ethernet Cable (K2.72033.0), which allows synchronizing the settings on one camera to the other.