GMPER100L PLANT!T Super Coarse Perlite, 100 L/3.53 cu ft Perlite is a unique volcanic mineral which expands from four to twenty times its original volume When expanded, each granular, snow-white particle of perlite is sterile with a neutral ph and contains many tiny, closed cells or bubbles The surface of each particle is covered with tiny cavities which provide an extremely large surface area These surfaces hold moisture and nutrients and make them available to plant roots Perlite is sterile, it is free of disease, seeds and insects