guttabeta® drain is a special dimpled membrane with laminated filter fleece for the highest performance. The filter fleece, made of tear-proof and decay-resistant polypropylene, prevents the dimpled structure from being filled with slurry. At the same time the membrane’s drainage channels always stay clear. This results in an efficient dewatering process and a continuously clear air chamber that permits more seepage water to drain than regular dimpled membranes.