Rockwool Slab 8" x 40” x 3" New & ImprovedWrapped in plastic to keep algae down to a minimum, and can be cut down to any length Excellent distribution of water to ensure optimum air water ratio Vertical Fibres The strong root development makes for perfect root distribution through the block and results in quantities of root tips at the bottom of the blocks that other blocks simply cannot match, guaranteeing fast rooting after planting Quantity A bail contains 12 slabs