FibreDust Coco Coir Block 1 block expands to 2.5 cubic feet (around 15 Gal) of growing medium after hydrating with 5 to 7 gallons of water Organics Material Review Institute(OMRI) Listed product High-grade coconut coir with low EC (Less than .8) and optimum pH levels of around 5.8 to 6.8, Prewashed to remove Salt Perfect for cuttings, seeds, plants, vegetables, hydroponics, mushrooms and worm farms Professional grade as used by Hydroponic and other large scale growers around the world