Applies on the backside, stomach and lower back heat to relieve muscular tension, especially in the thigh area. The sharp edge all around is perfectly designed for Guasha massage. 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: 3.8" x 3.2" x 1.1", 2 Pieces per Box.