High quality massage balls have spiky surface that helps in relieving tight muscles, especially those around the neck, back or shoulders. Often used in hands, under feet or on the spine and under the buttocks. As well as relieving muscle tightness, they help relax the user and can help to release toxins and improve circulation. The balls are supplied as a pack of two units and are different sizes to enable the user to target specific body areas and muscles as well as those being harder to reach and requiring a smaller ball. The smaller mass age ball is Green and 7.5cm in diameter. The larger massage ball is Purple and 9cm in diameter.