Triangular shape combined with innovative articulating harness has resulted in a vacuum that feels more like a part of your body. Weight of backpack is distributed to the natural center of gravity, so you have better balance no matter how you move. The die-cast aluminum tri-latch system assures air performance. Four level filtration with HEPA captures 99.97% of particulates 0.3 microns or larger, improving IAQ. Four Level Filtration w/HEPA: 1372 sq in total area.