This is the exercise seat that uses resistance-training technology to improve back and core strength. Unlike a standard sit-up that can strain the neck and back, this unit’s built-in resistance provides back support when performing the classic abdominal exercise and helps one achieve a more effective core-based workout. Its patented design utilizes internal interlocking springs that can be adjusted with built-in precision dials to provide 24-48 lbs. of resistance. The strengthener’s versatile design tones abs, obliques, quads, glutes, calves, forearms, triceps, and biceps through a variety of exercise positions. It requires only 21 3/4" x 20 1/2" of floor space, making it ideal for use in front of a TV with the included anti-slip mat and workout DVD. Folds for unobtrusive storage in a corner or closet. Supports users up to 250 lbs. 21 3/4" L x 20 1/2" W x 15" H. (13 lbs.)