Mono Serra's Zito blue underlayment creates an excellent protective moisture and mildew barrier for your vinyl or SPC floors. Equipped with a 1.5 mm high density membrane, it is suitable for electrical and water radiant heated floors. One roll covers up to 200 sq. ft. (3.58-ft wide and 56-ft long). Made from 100% new materials. Sound transmission class (STC) = 73. Insulation impact class (IIC) = 72.