100% Natural Black Basalt has No Wax, No Dyestuff, No Chemicals, No Radiation. Packed with a Natural Bamboo Box. Total hand shaped, High Standard 172 hours Water Polishing Technology Makes Sure It Has an Even and Smooth Surface. Increase Circulation, Vasodilation of Blood Vessels, Providing Important Energies, Increases cell Metabolism, Increase Pulse, Deep relaxation of muscles. Size: X-(7.6cm x 5.6cm x 2.5cm); XX-(11.4cm x 7.6cm x 2.5cm); XXX-(15.2cm x 8.9cm x 2.8cm) Create a feeling of balance and harmony, 8 Pieces per Box (X).4 Pieces per Box(XX)(XXX).