Allowing users to replace only air filter media, reusable clamshell or thin envelope air filter frame fits in spaces less than 0.25 in. thick. It can be removed for service while continuing to reduce risk of disturbing dust loaded on filter. Frames are also open for access to replaceable media for cleaning and substitution. RoHS-compliant frame meets UL 94 HF-1, ATCA, UL 900 Class 2, CE, Telcordia, NEBS GR-78-CORE and GR-63-CORE, micro TCA, and ETSI standards.