To be used in hot massage to relax and relive tension of the muscular stains in the feet. Each fit comfortably between each toe, providing heat and release to each toe. 100% Natural Black Basalt; Excellent for holding heat for long periods of time; Rich with iron and magnesium. Shaped and polished by traditional handcraft, no wax, dyestuff, chemicals were applied. Size: 1.5' x 1' x 0.3', 8 Pieces per pack.