Grodan rockwool slab is the most widely used throughout the world by both commercial and hobby growers. It represents the finest in Dutch Growing Technology. These new generation slabs from Grodan replace the Expert slab and offers the same superior quality. Due to its more open fibrous structure faster root development can be achieved in addition the slabs are simpler to water and safer to buffer. The nature of the new fibres also provides a firmer slab which enables a stable root volume right up to the end of the cultivation cycle.