Constructed from high-quality, durable material, the Aktiv Stability Ball is a great tool to increase core stability, posture, balance and flexibility. Use it for exercises such as sit ups, push-ups, squats. planks, hamstring curls and hip lifts. The unbalanced surface forces deep stabilizing muscles to engage throughout every movement, effectively enhancing and increasing muscle tone all over. The Aktiv Fitness premium line of functional exercise tools inspire and support today’s high-demand dynamic training environments.