Nispira 3-in-1 HEPA filter replacement compatible with Himox air purifier model AP01 H01. HEPA filter captures 99.97% of air pollutants as small as 0.3 microns. Preliminary filter captures visible dust and hair to extend the filter life. Activated carbon inside helps eliminate many common household odors and chemical smells. Dimension: 5.1 × 5.1 × 3.5". Suggest to replace every 6 months. 2 filters included