Natural Lava Basalt: You should determine the size before placing your order. Each stone is made of high quality natural lava basalt; this stone has good heat retention and gives a warmer massage to your body, ideal for spa, massage therapy. 10 small stones: each stone has the same size: 3x4cm. Fits feet, face, eyes and body. Pay attention to the size. Ergonomic Design: The curved surface makes the stone fit closely to your skin and avoid heat loss, the surface of the natural lava basalt stone will retain more heat, and the small size can be used for feet, face, eyes. Application: These massage stones can effectively massage and warm your muscles, deeply relax your body and improve your blood circulation. Suitable for people who use computers and mobile phones frequently.