Hot & Cold massage set provides effective relief from everyday aches and stiffness. Ergonomic shape roller contours to the arch of the foot and textured ball offers comfortable massage treatment. The liquid inside allows the products to maintain its temperature for up to 20 minutes of hot or cold therapy. Ball diameter: 7,5 cm, Roller size: 18,5 cm x 8,2 cm. For heating: in warm or hot water (no boiling water, no microwave allowed). For cooling: freezer (max 5 hours per time).