Strengthen and tone your muscles with the PTP Combo Pilates balls. Suitable for all fitness levels, they can be used for working your coordination, balance and flexibility in leg, arm and abdominal exercises or as a supportive base to improve the body's alignment. Versatile, compact and lightweight, the set features a small (15 cm - 5.91") and a medium (22 cm - 8.66") size ball allowing you to do a wide variety of exercises with different levels of assistance or resistance.