GVS Elipse A1-P3 RD ready-to-use half face mask, SPR503 Features Activated carbon has a specific pore structure for maximum surface retention efficiency and an ideal pore size for optimal respiratory resistance. The masks have two activated carbon filtration structures for protection against a range of gases, vapors, dust, and mist. After the filters fill, they can be replaced with spare filters. These filters provide protection against various substances up to 1,000 ppm...xTLV and up to 50 TLV for dust and mist.