HydroDynamics Crop Circles Premium Coir Fiber, 5 Disks An organic potting medium made from natural coconut fibers, this medium is ideal for hydroponic and mixed media cultivation Each Crop Circle disk expands to about five times its compressed size Crop Circle disks are a shredded form of coco, as opposed to the coffee ground consistency of competitive products, which results in a much higher air to water ratio, extremely important for healthy root development