Activate your core musculature and build up your balance with an MD Buddy Exercise Ball – available in 55 cm. Rolling unpredictably, a stability exercise ball forces you to keep your ab, leg, back and upper body muscles in constant motion. You’ll be rewarded for that effort with improved posture and greater flexibility and increased overall strength and fitness. It’s the perfect accessory for yoga and pilates, not to mention body-defining exercises like knee tucks, glute bridges, push-ups roll outs, Russian twists, and planks. Deflated, they’re light and portable so you can take them with you anywhere.