If you recycle abrasive, this abrasive sifter screen is a real time saver. Contaminants, such as bits of paint and rust, mix with the abrasive as it is recycled in the blast cabinet. These pieces can clog the nozzle. To keep the abrasive free of these particles, simply empty the abrasive regularly through the lower valve. Then pour the abrasive back into the cabinet through the sieve. If the abrasive can pass through the sieve, it will also pass through the nozzle.