Stonewool is recognized the world over as a dependable hydroponics growing medium and Grodan stonewool in particular is known for its quality, consistency and performance. Once plants develop a healthy root system in the smaller stonewool plugs and blocks, they're transferred onto one of these larger Delta Slabs for the remainder of their growing cycle. This single Delta Slab is wrapped in a biodegradeable, UV-resistant sleeve for easy handling and algae
prevention.