The turnbuckle conveniently attaches to either end of your Zipline. To install the turnbuckle, simply attach one eye bolt to one of the looped ends of the cable; either the pre-looped end or the loop that was made from the u-bolts. Next, attach the other eye bolt end of the turnbuckle to the two loops from the sling cable that is wrapped around the opposite tree. Twist the turnbuckle to fine-tune the overall tightness of the Zipline course, and adjust occasionally so the cable stays tight.