Perlite 3-6mm (50 Litres, approx 4.5kg)Natural Expanded Volcanic Perlite is an ultra light mineral that improves soil structure. Low in density, its pocket of air keep soil from compacting around it, allowing roots to easily reach deeply into it. The Natural Expanded Volcanic Perlite is used to improve the drainage and aeration of any growing medium. The aerated soil drains water effectively, but retain enough moisture in itself for the root of the plant. Its high porosity makes it perfect