Did I buy the 12 cm version. Ball, cozy circles on the wall and then vigorously up and down thrust Bern, back and herrollern, whatever you want. And with the pressure that you want. Whether upper back, lower back or hip / thigh side, you can go anywhere, the use is convenient, labor-saving and extremely efficient. The tennis ball I've ever used, is disposed of. Too small, too soft and slips away on the wall. 10 stars for the Black Roll Ball and absolute buy recommendation.
