Harvia 5-10cm Natural Split Face Sauna Heater StonesSplit face sauna stones are recommended for electric sauna heaters and wood burning stoves for the best performance. Split face stones store more heat, so that the water thrown onto them will evaporate efficiently on the broad stone surface. Harvia split face sauna stones stack easily and allow better air circulation, which improves the durability of heating elements. Harvia sauna stones are selected to provide bathers with an intense, soft heat.