GYM BALL 2in1: the Spokey HALF FIT is made of non-slip material. This is helped by the circumferential stripes on one half of the ball and the massage protrusions on the other half. The main task of the massage protrusions is to stimulate blood circulation and to massage the body, which leads to quicker muscle regeneration. It uses the Anti-Burst system, which ensures a slow and gradual release of air in the case of a puncture. This is very important for the safety of the user, who is given time to react (dismount).