This is an extra backup connector that comes in handy. 
 
A Biothane backup connector. Connector measures 270mm long in total and is 1/2" wide.
 
What is the backup connector for?
 
Attach to your dog's backup collar and to the square (or round) section of the snap hook on leash. Or if you use harnesses and have an escape artist, clip from harness to collar in case your pup wiggles out during a walk.