3-Layer Purification Filter Box 4" with High Efficacy Hepa and Carbon Filter, Fit 4 Inch Inline Duct Fans for Fresh Air Intake and Ventilation System

Filter box designed for use with inline fan, the airflow generated by the fan will pass through the filter box, where it will be purified, ensuring that the air exiting the filter box is clean and fresh | Selected high quality granular activated carbon, which can effectively eliminate indoor odors and formaldehyde, and keep the indoor air fresh and clean | Durable Construction: Made from high-quality, corrosion-resistant stainless steel materials for long-lasting performance | Includes 3-Layers Filter: Pre-filter, activated carbon filter and HEPA filter. Multi-layer filtration provides fresh air and blocks dust and odors | Fits 4" Inline Fans: Filter box dimension 11.81 x 7.87 x 7.87" | 300 CFM Maximum | Pre-filter size :16.73 x 10.63 x 0.79" | Activated Carbon Filter:16.73 x 10.63 x 0.79" | HEPA Filter: 16.73 x 10.63 x 1.97"