replacement - ensures seamless integration and compatibility with for Kickr Core If the ball is badly worn or needs to be replaced, you can easily remove the old ball and install the one without any complicated operations. Ensures excellent stability during long, intense indoor cycling training This design not only increases the stability of the product and ensures the safety of users during exercise, but also effectively prevents floor wear Relieve pain with increased movement and comfort with our bike rocker ball feet Improve balance and work your core muscles - Breathe life into a once motionless trainer ride. Increasing the amount of movement increases mental and physical engagement. The bike replacement rocker ball adds extra movement to work your core muscles and overall balance, ensuring you maximize every second of your indoor training time. Colour:Black Material:plastic Package Contents: 4 x Shock-absorbing foot pads (without ball) 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.