The SDL Atlas M021A Air Permeability Tester is used for fast, simple, and accurate determination of the air permeability of all kinds of flat materials and of foam cubes. The measuring range covers dense papers and airbag fabrics as well as extremely open non-woven and forming fabrics. A specimen is clamped over the test head opening by pressing down the clamping arm which automatically starts the vacuum pump. The pre-selected test pressure is maintained, and after a few seconds the air permeability of the test specimen is displayed in the pre-selected unit of measure.