No need for complex installations or modifications. Simply attach and enjoying a more stable ride. high-grade materials, this stabilizer leg is built to withstand the rigors of intense workouts. Dual Tennis Balls for Optimal Comfort: Equipped with two high-quality tennis balls, this accessory cushions your feet and distributes weight evenly, creating a more comfortable riding experience, and decreasing static pressure on your joints - reducing knee pain and stress on your fancy carbon bike frame! Elevate Your Experience: with Feet, enhance your indoor cycling experience by adding stability, comfort, and efficiency to every workout. Together, they provide a dynamic and effective training experience. Enhanced Wobbling for Indoor Training: These adapters accommodate 2 tennis balls (or any other 65mm balls) each, offering a comfortable side-to-side motion during intense indoor cycling sessions and minimizing the noise transmitted through the floor - ensuring your downstairs neighbors are just as delighted. Color: Black & Green Material: plastic Specification: Package Contents: 4 * Feet Adapters 8 * 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.