3M™ 701 Cartridge/Filter Adapter, Plastic, Black/Orange for 7800S Full Facepiece Respirator - Premier Safety
3M 2091 Particulate Filter P100 S-17120 - Uline
3M 701 Black/Orange Filter Adapter - 051138-29113 [PRICE is per BAG of 2]: Safety Respirator Cartridges And Filters: Amazon.com: Tools & Home Improvement
3M 5P71 & 5N11 filter adapter to attach filters to cartridges.