TRNR Gym Ball 75cm - BlackThe 75 cm TRNR Gym Ball is a must have training tool, delivering greater core strength, balance, coordination, range of motion, joint stability, and postural alignment. By adding instability to your workouts, your deep abdominals, back and pelvic floor muscles have to work harder to keep you in position. This makes it ideal to strengthen these often neglected muscles, preventing muscle imbalances, back pain, and injuries. Though specifically designed