The strong NRS Tow Tether, with built-in bungee, is used with the quick-release harnesses on rescue life jackets.
 Stretched length is 53", unstretched is 33"
Add 6" to length for carabiner and metal O-ring
The stainless steel O-ring includes a hook patch of "hook and loop" material that facilitates centering of the O-ring on vests that have the loop material sewn on in the back.
The Tether also has a hook patch on the carabiner end. This mates with a loop piece available on some rescue PFDs, forming a quick-release holder for the carabiner.