Athletes, fitness junkies, beginners and rehabilitation patients alike have been searching for a resistance band that is as effective at doing its job as they are about reaching their goals. Now, there is one! The unique construction of the DartBand allows it to be worn during most any movement or exercise you can imagine. Performing a movement while using progressive resistance causes the body to recruit more muscle fibers while allowing you to work through a full range of motion. Progressive resistance also encourages proper form which can reduce one of the leading causes of fitness related injuries. Whether you are training at the gym, practicing drills on the court, sprinting down the field or managing your rehabilitation, the DartBand will be there too. This is the resistance band that can truly be as mobile and hard working as you are. The design and wearability of the DartBand provides unmatched versatility allowing you to enjoy all the benefits of resistance band training without the issues. It is great for improving strength, speed and endurance as well as increasing flexibility, agility and muscle fiber recruitment. The X-Heavy DartBand is the perfect resistance for those who are serious about pushing the limits in their workouts. Because this extra heavy band will push your training to the max and is not for the faint of heart. It is made of 100% medical grade tubing which provides 15 lbs. of resistance at 100% stretch to 138 lbs. of resistance at 600% stretch. The X-Heavy Accessory Pack includes the X-Heavy DartBand (Grey), a carabiner and one heavy duty door anchor. This combo is the perfect trio to get the max amount of usage out of your sweat time! From yoga to body building and post-surgery physical therapy, this game changing design is revolutionizing the world of resistance band training.