SportsArt A957 is a leg extension machine designed to strengthen the quadriceps muscles in your legs. It features a rotator that allows you to adjust the angle of the movement to target different parts of the quadriceps. The plate adjusting pin lets you set the starting position of the movement, while the rotating range adjusting pin allows you to shorten or lengthen the range of motion. The leg cushion is movable, allowing you to find the perfect position for your legs. The machine also has a minor weight stack that you can use to add additional resistance to the exercise. Finally, the belt is adjustable, so you can customize it to fit your body.