The balance ball on the joystick board is made of high-quality wear- materials, ensuring excellent stability during long-term, high-intensity indoor cycling training. This design not only increases the stability of the product, ensuring the of users during exercise, but also effectively prevents the floor from being worn out. Embrace the suffering but ease the pain with added movement and comfort by our Cycling Rocker Balls Feet. Combined with the proper plates, these Diameter balls provide 10° of total horizontal motion to help you to move with the bike rather than against it decreasing static pressure on your joints while you crank out your indoor sessions on for Kickr Core. Breathe some life into your once-motionless trainer rides. With the added movement comes added engagement of both mind and body. The Cycling Replacement Rocker Balls add that extra motion to target your core muscles and overall balance ensuring you maximize every second of your indoor training time. Choose our replaceable joystick balance ball to make your indoor cycling training more stable, efficient, and safe! Upgrade your cycling equipment quickly and enjoy a more enjoyable sports experience! Type:B:Without Ball Colour:Black & Green Material:Plastic Package Contents: 4 * Feet Adapters Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.