TrailMax Original in-Line Swivel Four Horse Highline Kit This kit is recommended for Leave No Trace Backcountry Ethics, National Parks and many State and BLM lands. On a high line, your stock can walk around in a circle, lie down and even roll. The In-line Swivel functions as a knot eliminator and allows your stock to walk in circles without unraveling the lead rope. The tree savers are recommended or required on almost all state and national lands so that trees are not girdled. Includes easy-to-follow set of instructions to help protect both the environment and your stock from injury.