Re-Traxt 4-SC for Descent PFD (#637050) Shock loaded tubular webbing absorbs impact from towing and stows compressed, close to your side. SC - "Self centering" model with velcro tab that mates up with the velcro on the back of the Descent PFD. Adjustable so user can select mating placement on back so web rides in close at your side. Comes with a special wide gated paddle biner and black oxided stainless steel ring as shown.