Cultiwool 1.5" x 1.5" x 1.5" Cubes w/ Shrinkwrap Cultiwool Rockwool Blocks have an optimum air/water ratio for healthy root growth and allow for great continued rooting thanks to the extremely even distribution of water and EC. These blocks have an excellent water absorption and (re)saturation rate and feature the exclusive Plant Comfort fibre structure which has a lower density of resistance during rooting with no loss of firmness. All blocks except the 3" x 3" x 3" also have the Optiplus feature, which is a unique design on the underside of the block allowing for excess water to drain away easily. Cultiwool 1.5" x 1.5" x 1.5" Cubes w/ Shrinkwrap are sold by the case. Specifications