J-DRAIN 400 RB consists of an impermeable polymeric sheet cuspated under heat and pressure to form a high flow dimpled drainage core. The core is then bonded to a layer of roof resistant filter fabric. Specifically designed for Green Roof applications. The root resistant filter fabric prevents roots from affecting the efficiency of the drainage/aeration layer and retains soil or other fine particles from being washed away and allowing water to pass into the drainage core. The collected water is then conveyed to a proper collection system.