Unfortunately, the ball is too hard for me to work with four fingers simultaneously. If I put all four fingers and press, then pain the joints of my middle finger, before I even feel a strain in the outer fingers. The resistance is in the middle plane significantly higher than the outside. Also training with only two fingers, I dare not really, because pressing this Balls - for whatever reason - my joints felt burdened very unhealthy. I therefore use only the Thera-Band hand exerciser (in black - extra hard). I climb or bouldering otherwise 1-3 times a week and am therefore not entirely untrained.
The surface of the ball is Slightly granular and has a sort of anti-slip effect. Unfortunately that did that dirt and lint stay tuned result, immediately adhered to and not abzubekommen without water. Cleaning with water is however very simple. Simply rinse and let air dry.
