I purchased the 900 to increase bodily coverage after using a small mat for a year. My diagnosis is osteopenia with an orthopedist assessing bone on bone in both knees last March. I definitely feel that carilege is being regenerated as my movement is steadily improving, despite many medical authorities stating that's not possible. Anything that I can do to support mitochondria and stem cells is a step in the right direction. Age 82, and this BioMax 900 may be the best investment I've ever made.