ProsourceFit Exercise Balance Pad, Non-Slip Cushioned Foam Mat & Knee Pad for Fitness and Stability Training, Yoga, Physical Therapy

https://a.co/d/06ciYh8b

A cushion like this works really well: https://www.amazon.com/ProsourceFit-Exercise-Non-Slip-Cushioned-Stability/dp/B0766565HG