Listed by the Organic Materials Review Institute (OMRI), coconut based Sunleaves Coir Bricks and Blocks are derived from an abundant, renewable resource that retains air and moisture incredibly well. Great for amending soil and soilless mixtures, Sunleaves Classic Coir is finely shredded coir material compressed into bricks and blocks: a preferred choice among African violet enthusiasts. PieceCoir Bricks and Blocks feature larger mulch-type coir chunks and chips for greater root penetration, making them ideal for hydroponics gardening. Coir bricks expand to approximately 1/3 cubic foot when soaked in water while the larger blocks expand to an impressive 2.5 cubic feet.