This is a Shutter Release Cable for Nodal Ninja Mecha. The cable ensures camera triggering and focus lock. The CAM port on the Mecha is compatible with many 2.5mm 3rd party stereo remote shutter cords.
Not intended for pan and tilt Mecha heads (NN3 and NN6). For pan and tilt Mecha heads the long coiled cable must be used.
The long version is also available for more camera models so if you can't find the short version for your camera take a look at the long cables for more options.
Mecha CAM port accepts 2.5mm stereo plug. The other end of the cable must have the same plus as the the original remote for your camera. This makes sure the camera side connector is compatible to your camera.
Similar cables are used in various third party remote switches with replaceable cable. Another commonly used remote side connector is 3.5mm which is not compatible with Mecha CAM port.
For long version of this cable look here: long coiled cable (available in more variants).