Coconut coir bricks are composed of three different types of compressed coconut coir. This high quality, low sodium growing medium is an environmentally friendly alternative to sphagnum peat moss. When hydrated with water, bricks and blocks rapidly expand which saves you time and effort. Comes with 1lb of earth worm castings when mixed with coir the media is rich with enzymes and nutrient for you plants. They can be exclusively used by themselves, blended together or mixed with expanded clay pellets, perlite or topsoil. The brick will break down on its own in three years. Is great for mixing into your soil mixtures and can be used as a standalone growing media or mixed with perlite, vermiculite, grow rocks or any of your favorite soil additives. Incredibly strong, it makes a better candidate for use with enzyme products that convert roots to biomass. Each brick makes up to 18 Gal (72 Quarts, 2.5 Cu Ft, 68 Liters) of ready-to-use soilless media. Viagrow 5KG bags are biodegradable and environmentally friendly.