The HarmonyTM Professional Yoga Mat is made with open cell, natural rubber, you can say goodbye to slipping on your practice mat - even if it gets wet with perspiration. Natural rubber has long been used where safety demands non-slip performance. Harmony takes advantage of the non-slip properties of natural rubber - resulting in the best slip-resistance on the market. Harmony is constructed of natural rubber a renewable resource tapped from rubber trees - containing no PVC or ozone depleting substances - perfect for the yogi concerned about the environment.