A deep tissue massage tool ergonomically designed to protect practitioners from occupational injuries. It allows therapists more focused deeper work with less physical effort. The contoured knob grip encourages neutral wrist positions while working. 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: dia.2.5' x 6'