Crop Circles Premium Coir Fiber is an innovative organic potting medium ideal for hydroponic applications. These Crop Circle disks are made from natural coconut fibers, which allows them expands to about five times their compressed size. Each disk fills a one gallon container. The expansion of this shredded form of coco results in a much higher air to water ratio, and therefore facilitates extremely healthy root development. Crop Circles are entirely organic and manufactured from renewable resources. Dimensions of compressed disk 5" diameter x 1½" thick. Can also be used in mixed media applications.