Dimensions - 6cm diameter Material - PVC Hardness's Grey - Hard Green - Medium Blue - Soft [spec] Specification If you are in need of a sports massage at home, look no further. Our Fitness-Mad massage ball set has three different hardness's; ideal for acupressure, tension and trigger point release. These balls can be used for a full body massage, from your neck to your calves! If you'd like a serious massage, we recommend using these balls in conjuntion with a foam roller for additional release. Easy to transport to and from the gym! [/spec]