Mortairvent is a mortar deflection and ventilation mat used behind manufactured stone, natural stone, stucco, EIFS, and brick. The gray filter fabric acts as the mortar deflection, while the blue polypropylene matrix creates a dry cavity allowing for proper drainage and ventilation. The use of Mortairvent can reduce the chance of rot and mold within a wall system. Advanced Building Products Inc. 800-252-2306.