The 1600 Series Sewer Vent is cast from 356-T6 aluminum alloy for light weight construction. The valve is then powder coated the a green epoxy that is highly resistant to sewer acids and gases. It is finished with a green coating that blends in nicely with the existing environment. A 1/4" x 1/4" protective mesh screen keeps debris and insects form entering the vent pipe while maintaining the required open area for municipal use ( 1.25:1 ratio ). Alternative materials are available upon request.