No, I think you will find that it is basically a tail rubber and run ring or Large bore swivel(a la Korda)set up to a swivel then your rig off the other end of the swivel-either Quick change,Gemini clip(my favourite)or tied direct.
put on the run ring(john roberts or similar) then the tail rubber then tie on a swivel (or Gemini clip as i do)and pull the rubber down onto it so that the swivel dissapears inside and the run ring then slides onto the tail rubber until tight,very safe and provides a cheap way of bolt rigging without the need for too many gizmos also easily pulled away from the rubber in the event of a break off
hope that explains it
Regards Matt