The patented air channeling system between the outer shroud and inner firebox allows heated air to efficiently pass through the rock chamber for faster and more even heating of the rocks. This improves steam generation and air circulation in the sauna. As the fire dies down, the firebox walls cool and the air stops rising through the rock compartment and is redirected to the side vents. We call this the “Coanda” effect. The stones retain their heat longer, providing long-lasting comfort while using firewood as efficiently as possible.