PLANT!T HYDROPONIC CLAY PEBBLES POROUS ROCK + TWIN CANARIES CHART - 1 Liter / Quart Bag Extremeley stable in both pH and EC Made from 100% natural clay trong structural integrity means that they are less likely to break and compact, which helps to preventdripper systems from getting blocked Pre-washed to aid in stability Drain freely and do not hold any excess water, providing good oxygen levels around the root; suitable for flood and drain systems, multi-pot and drip feed systems