Keeps the tire chains tight and in place - thus maximizing the life of the tire chains. Especially on large tires such as farm tractors, loaders, and graders, it is extremely difficult to take the slack out of the tire chains. Our Spring Tire Chains Tensioners are fully adjustable and are a must for best performance. These large spring tensioners are extremely heavy duty and weigh 12 lbs per set. Competitors sell the same tractor tensioner for over $120 per pair. We price ours at almost the 1/2 price, since we know how important it is to have tight tire chains and everyone should use them. Mounts to the side chain on the outside of the tire. One pair per set is recommended.