Anti-burst system Our exercise ball is made of high-quality PVC material and Anti-burst honey comb structure. Anti-burst system mean PROIRON exercise ball only slowly deflate instead of bursting when exercise ball is pierced by sharp objects Anti-slip surface The fitness ball has a non-slip surface, which is essential for a safe workout. Eco-friendly material for gym ball won't irritate your skin. Each PROIRON gym ball comes with an easy-to-use hand pump. It is also perfect as OFFICE BALL CHAIR to improve your Core Strength Extra thick exercise ballOur exercise ball have thicker wall in 2mm than normal yoga ball (withstand up to 300kg), made with top quality material, free of BPA & heavy metals Pick the right ball According to your height -- 55cm ball for 150-168cm; 65cm ball for 168-180cm; 75cm ball for 180-190cm approximately.