This is our 6 inch ergonomic wheel for back pain relief!
When placed between your lower back and your chair / floor / wall it will stretch and open up your vertebrae plus encourage good posture.
Included is a 3D model for the wheel as well as for the ring which, when printed in a flexible material will add to durability , grip and comfort. The center groove is there to fit to your spine.
Your material costs will be about $5.