Hoyrykivet, Steam Stones for Sauna Stove - 2 PackWhile traditional sauna stones let the water evaporate on the surface of the bricks, the Hoyrykivet steam stones feature 4 small chambers. The 4 holes act as a reservoir and collects approximately 1. 35 oz of water and sauna fragrance oils when in use. As the water starts to gradually warm up, the vapors mixed with fragrance oils are evenly evaporate into the air calmly and continuously.