This has the metal ring sewn on at one end and the karabina goes through a stitched loop at other end. A cowtail is a length of mountain webbing, which is hollow. you then pass shockcord through the middle and stitch into place. It attaches to any buoyancy aid with a chest harness. if you are resuing from a bank you should attach youself via the cowtail and a throw bag to the bank, preferably another person, but a fixed rock or tree will often work in an emergency. Then if you go for a swim there is a way of pulling you back in. The cowtail reduces the jerk by acting as a spring.