A rock tower heater with 50 pounds of rocks and BioWater Technique (BWT). Match with the Pure 2.0 or A30 sauna control. For rooms from 65-310 cu. ft. The BWT (BioWater Technique) uses an integral water tank to provide two different sauna experiences from the same heater. The Piccolo used with water in the BWT provides a lower heat (140-175°F) with more humidity for a gentle sauna experience, or the Piccolo can be used like a traditional sauna heater with temperatures ranging from 175-190°F with humidity adjusted by ladling water over the rocks.