C.A.P. Grow Blocks are easy to use, 100% self-contained and made with premium expandable soil-less coir based substrate enclosed in an inert permeable fabric. This revolutionary design allows the grower to enjoy all the benefits of a premium loose substrate without all the hassles of preconditioning Rockwool or having to handle and blend a loose mix. Simply add water and allow the substrate to expand. Mini and mighty, these little guys may just become your new favorite grow media.