This respirator is a 6000 series full facepiece (small) with a single DIN thread port on the front of the facepiece. It is NIOSH approved for use with the 3M™ Cartridge FR-C2A1 or 3M™ Cartridge FR-64 for acid gases (including chlorine), CN, CS, and particulates (P100 filter). The FR-C2A1 cartridge meets military specifications MIL-C-51560 and EA-C-1704.