Harvia Virta HL90E is a 9kW electric sauna heater engineered to power sauna rooms up to 494 cubic feet (CF). Required control and sauna stones 100 lbs (3 boxes) sold separately. Sidewall or corner, floor mount install For sauna rooms from 177 to 494 cu. ft. Requires a minimum of 100lbs of stones (3 boxes-AC3020) 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).