Horticultural Grade Perlite. A natural-safe way to improve your soil. Perlite is a volcanic mineral in granular form. It is expanded by heat. It is completely sterilized. A natural way to loosen soils to allow maximum root development. Helps to improve drainage and aeration in any soil and is hightly recommended for use in potting mixes. Includes an 18qt (0.700006 cubic feet) bags of perlite.. Due to changes in shipping regulations, we cannot ship this item to California.