A gym ball, also known as an exercise ball, stability ball, or Swiss ball, is a large, inflatable ball made of durable, anti-burst material. Typically ranging in size from 55 to 75 centimeters in diameter, these balls are commonly used in fitness and rehabilitation exercises. The ball's instability engages various muscle groups, promoting core strength, stability, balance, and flexibility. Gym balls are versatile tools that can be incorporated into a wide range of exercises, including core workouts, stretching, and resistance training. They are widely used in fitness studios, home gyms, and rehabilitation settings to enhance overall fitness and well-being.