MD-3639 is a moisture diverter above wall openings for our WEEP System; it’s part of a technologically advanced design for creating division between the masonry and structural back-up walls. MD-3639 is 24 gauge galvanized steel 2.5″ wide and 4′ long; bent into a “V” shape with one leg 0.625″ long and one leg 1.875″ long at an angle of 65°. It stops moisture and diverts it to either side and away from moisture-sensitive wall details.