The patented smart toner features a revolutionary flexible sleeve designed to protect the rubber tubing from overstretching, premature breakdown, and wear for maximum safety and comfort for the user. Durable and made from the highest quality materials, the smart toner lasts longer than traditional tubing and holds up against the most rigorous training conditions. The smart toner measures 4 feet in length and can stretch up to 4 times its length. Perform a variety of high-performance exercises comfortably without the irritation of latex against skin. The smart toner resistance tubing 3-pack includes light, medium, and heavy resistances along with door attachment and exercise chart.