Premium A+ Grade Sauna Stones set - Each sauna stone is similar in size, weight, and color. Each sauna box weighs approximately 35lb/16kg. Durability - These volcanic stones from nature possess long-lasting high-temperature resistance. Heat Balance - The surface of saunas stones has numerous fine pores, allowing them to easily absorb and evaporate moisture, evenly releasing heat and steam into the air. Ultimate Relaxation - Typically used on dry sauna heaters, using them 2-3 times a week helps promote health through the experience of profuse sweating. Recommendations - Sauna rocks absorb moisture well.