Enhance your sauna experience with Harvia Black Vulcanite Sauna Heater Stones. These premium quality stones are specifically selected for their superior heat retention and thermal conductivity, ensuring efficient steam production and a luxurious sauna experience. Their volcanic origin, dating back approximately 2000 million years, makes them incredibly durable and heat-resistant. These dark grey stones turn a striking black when wet, adding a touch of elegance to your sauna. Ideal for electric heaters and as a top layer for wood-burning heaters, these stones offer excellent heat storage and easy stacking for optimal air circulation.