Strong tether to be used as a tow line when clipped into the rescue ring on Swiftwater PFDs. The Short tether has a bungee to make the tether shorter when it is not in use. The Long tether has a tension string within and a barrel lock which allows you to adjust the length slighlty. Short Tether 36: 16" (Sretches up to 36") Long Tether 63: 63" (Does Not Stretch) Add 6" to Length for Carabiner and O-Ring