GenuineHarvia sauna stones are selected according to old traditions and convey a genuine sauna atmosphere. Harvia sauna stones provide good and soft heat. 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 the fracture. Angular split-face stones also allow for loose placement of the stones, which is the most important requirement, particularly in electric heaters in order to make it possible for the heat to be conveyed to the sauna room between the hot stones and heating elements. Good air circulation in the stone space makes the electric heating elements last for as long as possible. CAUTION: Light (ceramic), soft (soapstone), and smooth (rounded) sauna stones do not produce the desired results and they may cause problems in electric heaters in particular. 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). Durable with high-heat capacity Stones range from 4" to 6" (10-15 cm) To ensure optimal performance and safety, each sauna heater requires a specific number and size of stones. Refer to the guide below. Legend- 16kW - 264 lbs (120 kg), 4-6" (10-15 cm) - 6 × 44 lbsLegend- 21kW - 440 lbs (200 kg), 4-6" (10-15 cm) - 10 × 44 lbsLegend- 23.5kW - 572 lbs (259 kg), 4-6" (10-15 cm) - 13 × 44 lbsLegend GreenFlame- 15.9kW - 440 lbs (200 kg), 4-6" (10-15 cm) - 10 × 44 lbsLinear 16- 15.7kW - 88 lbs (40 kg), 4-6" (10-15 cm) - 2 × 44 lbsLinear 22 GreenFlame- 15.7kW - 88 lbs (40 kg), 4-6" (10-15 cm) - 2 × 44 lbsM- 16kW - 66 lbs (30 kg), 4-6" (10-15 cm) - 2 × 44 lbsM SL- 16.5kW - 66 lbs (30 kg), 4-6" (10-15 cm) - 2 × 44 lbsPro- 24.1kW - 88 lbs (40 kg), 4-6" (10-15 cm) - 2 × 44 lbsPro- 26.6kW - 111 lbs (50 kg), 4-6" (10-15 cm) - 3 × 44 lbsPro- 31kW - 132 lbs (60 kg), 4-6" (10-15 cm) - 3 × 44 lbsPro SL- 24.1kW - 88 lbs (40 kg), 4-6" (10-15 cm) - 2 × 44 lbsForte- 4.5kW, 6.5kW, 10kW - 220 lbs (100 kg), 4-6" (10-15 cm) - 5 × 44 lbsVirta- 6kW, 8kW, 9kW - 100 lbs (45 kg), 4-6" (10-15 cm) - 3 × 44 lbsVirta- 10.5kW - 150 lbs (68 kg), 4-6" (10-15 cm) - 4 × 44 lbsVirta Combi- 6kW, 8kW, 9kW - 100 lbs (45 kg), 4-6" (10-15 cm) - 3 × 44 lbsVirta Combi- 10.5kW - 150 lbs (68 kg), 4-6" (10-15 cm) - 4 × 44 lbsVirta Pro- 16kW - 200 lbs (91 kg), 4-6" (10-15 cm) - 5 × 44 lbsVirta Pro- 20kW - 264 lbs (120 kg), 4-6" (10-15 cm) - 6 × 44 lbs