CFR › Title 21 › Part 868 › §868.526021 CFR §868.5260Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy link(a)Identification. A breathing circuit bacterial filter is a device that is intended to remove microbiological and particulate matter from the gases in the breathing circuit.(b)Classification. Class II (performance standards).