Refillable air filter assembly

A frame assembly for releasably maintaining air filter media, the frame assembly comprising:

• a thermoformed, plastic, integral body integrally forming a base, opposing side walls, opposing end walls, and at least one closure sub-assembly;
• wherein the frame assembly is configured to releasably retain the air filter media relative to the base via the closure sub-assembly;
• wherein the frame assembly is configured to, when in an open position without any air filter media, nestably receive a second, identically shaped frame assembly that is also in an open position without any air filter media;
• and,
• wherein the frame assembly further includes one or more capture arms extending from each of the opposing end walls and pivotable relative thereto, with the proviso that the opposing side walls do not comprise any capture arm or arms.