Add over 50 exercises to your fitness ball exercise program by adding Strapfitness and an exercise cord(not included) to your fitness ball. Workout all your major muscle groups using a fitness cord without the hassle or danger of the cord slipping. Strapfitness holds the cord where you want it and resistance can be changed by simply moving the cords position on the ball. Perform exercises on a fitness ball that were not possible until now! You thought your ab workout on a ball was good before? Now add resistance! The strap easily fits 55cm-75cm balls. Wt. 1lb