I had bought a cheap massage ball at Rossmann me some time ago. Unfortunately this was far too soft for my needs. I use the balls for tension in the back, as I am with the tense juncture lege and then rub with light movements. The balls are very strong and for people who are very sensitive to pain or pressure, there are certainly more appropriate products. For someone who likes a very vigorous massage, these balls are absolutely awesome. When it comes to smell, I can not report anything negative really. Clear is a the first unpacking a slight plastic smell engegen but had gone quite fast after some time outside of the package.