Description: 【Enhanced Stability 】: Crafted from quality plastic material, the indoor cycling snap rocker feet adapters with tennis balls provide exceptional stability during indoor cycling sessions 【Improved Comfort and Movement】: Designed to reduce joint stress, these cycling ball feet offer a 10° total lateral movement, allowing you to move your bike rather than against it 【Engage Your Core Muscles】: By adding extra motion to your ride, these replacement rocking balls help target core muscles and improve overall balance. This ensures you make the most of of your indoor training session 【Easy Installation and Replacement】: for due to wear or damage, you can easily remove the old tennis balls and install new tennis balls without any complex procedures 【Product Dimensions】: The indoor bike train stand rocker feet adapters measure 20 cm/7.87 inch, great cycling equipment to enhance your workout experience efficiently Specification: Material: Plastic Size Chart: 20 cm/7.87 inch Package Includes:2 Indoor Bike Train Stand Rocker Feet Adapters 4 Tennis Balls Note: Please allow slightly errors 1-2cm/0.39-0.79inch differences due to manual measurement.