Name:ShopiMoz 4-Wheel Ab Roller Wheel Abs Carver for Abdominal & Stomach Exercise Training with Knee Mat for Man and Women Material:ABS Height:12cm Width:6cm Net Quantity (N):1 Ab Wheel Roller has 4 wheel, which offers better support when rolling other than traditional ab rollers. Each repetition of the rollout exercise works will not only help improve your lower back strength but decreases your risk of muscular injury.