These premium quality cast aluminum cord tighteners are a rugged combination of carabiner and cam locking mechanism meant to secure, tension, and connect serious loads when paired with a rope or cord. Clip the carabiner to a fixed anchor point, then use the cam mechanism to safely connect, tension, and easily release your rope or cord.The CamJam XT aluminum rope & cord tighteners feature Nite Ize signature, knot-free CamJam tightening and tensioning technology. Available in two heavy-duty sizes and built from durable, cast aluminum, this rugged combination of carabiner and cam mechanism is designed to tighten, tension, connect, and secure serious loads up to 280 and 500 lbs respectively. The CamJam XT products feature a carabiner clip and gate on one end, and a rotating cam mechanism on the other. This clever design allows the CamJam XT to be configured in either a Fixed End or a Loop System to securely tie down lumber, gear, and other heavy loads. In both systems, the CamJam XT can be easily adjusted and re-adjusted time and again to tackle a multitude of tie-down projects over the years. The XT holds cord from 1/16"-3/16" [2mm-5mm] in width, and the XT Large holds rope with a diameter of 1/8”-3/8” [3mm-9mm]. To use the Fixed End System: simply anchor the carabiner to any hook, D-ring, or loop, and feed the cord or rope through the cam until you´ve reached the desired level of tension. Next, pull the cord firmly and the cam locks into place and stays that way until you release it. To use the Loop System: Tie a knot to create a loop in one end of your rope or cord. Clip the CamJam XT into that loop, then pull the other end or rope through the cam mechanism. This loop system enables you to bundle or wrap heavy loads and easily secure them. To Release the Cam: simply rotate the cam lock lever and pull your rope or cord upward.