After surgery for 2 meniscus tears and cartilage damage in my left knee and overcompensation wear and tear on my left, arthritis in BOTH knees AS WELL as a heel spur on my right foot, I had been at my wit’s end. Every step was painful. Painful may be too light of a word, every step was EXCRUCIATING! Well, I decided to give the M75’s a try. At first, they felt odd and I wasn’t sure that they were helping, but I kept with them and miraculously, within a couple of week’s, the “old spring” was returning to my step! Week’s later I am AMAZED! I can’t recommend them enough! They have changed my life! I just bought my second closet pack so I don’t have to change them out of my shoes as much or just maybe I will give some to my wife for her bad back!