These traditional, high quality sauna stones are noted for their durability and excellent soft steam created when water is applied. These stones are can be fitted in any sauna heater. They are available in two sizes: 5-10 cm and 10-15 cm. In the case that heaters require both grades, larger stones should be used at the base with smaller grade stones added to the top of the heater. Each box comes with approximately 20 kg of premium Harvia olivine diabase sauna stones