So far me the red ball is too hard, but the other two can be massaged well.
To loosen the upper back against the wall standing, I put my ball in a long sock; I can position it exactly without him rolling.
I find the balls practical and comfortable for my purposes than the so-called. "Hedgehog balls", but everyone needs to find out for themselves. Who has lying around at home a tennis ball, can this only once to test whether a massage with ball it is pleasant. If one takes the good, one of the three colored balls would allow a differentiated hardness selection.