Cozy Heat has taken the time-honored craft of building sauna stoves to a higher level. The part of the wood-burning heater that must be the strongest, the flame cutter, is made of sturdy, 5mm-thick stainless steel making COZY heaters extremely durable. This wood-fired sauna stove is hand-made in Estonia, where sauna bathing is a national tradition. Perfect for mild, long-lasting heat, the O TW is designed for pouring water over hot stones to create intense and luxurious steam for a more gratifying sauna experience. The Cozy Heat O TW wood-burning sauna stove features a through-the-wall design that lets you load firewood from outside your sauna. At the heart of the Cozy Heat O TW is its innovative circular rim design, which not only enhances the heater's aesthetic appeal, but also ensures efficient heat distribution throughout your sauna space. Installation and operation manual Stove utilizes 25%-40% less fuel than comparable sauna stoves Boasts minimal safety distances Sauna room sizes:12kW- 210 to 423 cu.ft.18kW- 317 to 635 cu.ft. Stone Requirements:12kW- minimum of 265lbs of stones18kW- minimum of 353lbs of stones 12kW- minimum of 265lbs of stones 18kW- minimum of 353lbs of stones 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).