Az (pre filter / coarse filter / air filter) is a filtering material mainly applicable for absorbing large dust particle in the air to prevent blockage in medium- and high-efficient filter so as to prolong their service life and efficiency. Models: Az-150g, 200g and 300g; Af-200g; Specification: general stock 1m*20m, 1.25m*20m, 1.6m*20m, 2m*20m. Also make according to customerf+s order.