Rounded Olivine Diabase sauna heater stones resemble nature's rounded stones from the great rapids, bringing a softer tone to your sauna along with multiple benefits. This stone introduces a soft steam method; the pouring water runs easily down to the lower stone layers. This way the water reaches more surface area, generating more steam with a softer touch. This method of using rounded stones on the top layer of the heater works in all sauna heaters. Only available with the purchase of a Harvia sauna heater or stove. Please note that each natural stone is unique in shape and size. We recommend purchasing an additional box of sauna stones to allow you to choose the highest quality of stone for fit, form, and function(Additional freight charges will apply). Refer to the guide below. R-991Spirit- 6kW, 8kW, 9kW - 110 lbs (50 kg), 2-4" (5-10 cm) - 4 × 33 lbs