Coconut coir bricks are composed of three different types of compressed coconut coir. This 11lb (5kg), high quality, low sodium, sterile growing medium is an alternative to sphagnum peat Moss & absorbs great amounts of water, lowering watering frequency. . When hydrated with water, bricks & blocks rapidly expand which saves you time & effort. 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. Better still, you can run it through a chipper & amend your soil with It. Incredibly strong, it makes a better candidate for use with enzyme products that convert roots to biomass.