Cultilène Stonewool OptimaXX slabs are for the final stage of planting. Recommended for larger long term crops with extensive roots such as peppers and cucumbers. The mainly horizontal fibre structure of the OptimaXX product ensures good root penetration throughout the slab and allows control of both water content and EC. The fibre structure ensures optimum exchange within the slab and accurate control of moisture content and nutrition. Typically seedlings in blocks are placed onto slabs. The Cultilène OptimaXX offers a well aerated slab in all seasons and the roots stay active as the excess water runs off quickly and efficiently.