Harvias larger sauna stones in the range of 100 to 150 mm are very well-suited for larger woodburning stoves and electric heaters such as Harvia Forte. Angular split-face stones also allow for loose placement of the stones. Split-face sauna stones are the only correct stones for electric heaters and woodburning stoves, because they can store lots of heat and the water evaporates efficiently from the wide surface of fracture.