Black Vulcanite Sauna Heater Stones 2-4 In, 44 lbs bring exceptional heat storage and striking visual appeal to both electric and wood-burning sauna heaters. Formed from volcanic material nearly two billion years old, these stones are naturally resilient, allowing them to withstand repeated high-temperature cycles without fracturing. Their 2–4 inch size supports easy, secure stacking that promotes proper airflow through the heater cavity, helping the unit warm efficiently and deliver steady, balanced steam. When wet, the stones turn a deep black, creating a dramatic contrast that enhances the look of the heater while contributing to smooth, consistent löyly. Suitable for use as a full load in electric models or as a high-performance top layer in wood-burning heaters, Black Vulcanite Sauna Heater Stones 2-4 In, 44 lbs provide durable heat retention, reliable steam production, and an elevated overall sauna experience.