2LBS Natural Expanded Clay Pebbles - It is lighter than ordinary soil, not broken after soaking, not easy to blow away, inert, pH-neutral, clean & decorative. 6 - 18mm Clay Ball - The size of the pebbles is perfect for small to medium pots and garden plants . Hydroponics Supplies - The clay pebbles porous structure provides excellent aeration for plants hydroponic. And prevents rotting, excess acidity. It stores nutrients like water and releases them to the roots . Great Growth Media - Filter water quality, retain water and nutrients.Combined with other soils media can activation soil,improve plant survival and soil fertility . Environment Protection - The clay pebbles is clean, tidy,dust free and no odor, Now It has been widely used in soilless cultivation of roof garden and lawn.It can be reused after cleaning. Malifea Clay Pebbles