Pargro Slab, 9.5" x 8" x 4", case of 16Pargro is lightweight stone wool made from basalt rock. Its a highly uniform substrate thats pathogen, disease, and seed free, offering consistent plant growth. Stone wool is inert, so it will not add or hold back any nutrients, giving you complete control over your plants. Pargro media has rapid water distribution and excellent re saturation capabilities, making it easy to use. The Pargro family of products are made in the most popular sizes that