Orangetheory Fitness - Bosu Ball | Your abs will work double-time when you try to remain stabilized on the Bosu Ball. The v-up portion completes this move for a total ab workout.
Reebok 65cm Medium Weighted Stability Ball, Pump Included - Walmart.com
Amazon.com: Reebok Gymball - 55cm Exercise Ball with Dual Textured Non-Slip Surface for Maximum Grip - for Core Workout, Improving Stability, and Posture at Home or The Gym - Pump Included -