### Dual Layer Two-stage Filtration Structure HEPA13 front layer traps ultrafine particles, back activated carbon layer absorbs TVOC, formaldehyde and printing odor. ### High Density Honeycomb Activated Carbon Honeycomb porous charcoal owns bigger adsorption space, longer usage cycle than common loose carbon filter. ### Full Surround Foam Seal Design Elastic foam wrapped around filter perimeter to avoid air leakage and guarantee full exhaust filtration. ### Standard 2-4 Months Replacement Cycle Balanced filter density prevents fast clogging, regular change every 2 to 4 months keeps clean inner air. ### Tool-free Quick Replacement Operation Open side cabinet cover directly, pull out used filter and insert new filter in short time.