Rockwool Slabs by Grodan - IP 30/75 12" wide X 3' long X 3" tall. WrappedSlabs are used to grow a variety of crops. Tomatoes, peppers, other plants can be easily grown by planting first into a smaller cube then transferring it onto the larger slab. Holes are cut in the top of the slab, the same dimensions of the cube. Some growers will simply cut an x in the plastic top, fold the side up and slip the cube in. Then they tape the folded slab plastic to the smaller cube. This keeps light out and when the top cube is used for a feeding point, it keeps the plant nutrient in. The bottom and ends are sliced to allow the nutrient to flow out of the slab.