The AMX FX25 3-Layer HEPA Filter Box is made from a high-quality DKP material with an electrostatic powder coating for protection. This gives it a smooth sleek surface with heat resistance and anti-corrosion properties. Its 3-layer protection filtration system offers protection performance for ventilation. The Primary efficiency filter, Activated carbon filter, and HEPA 12 high-efficiency filter purify your air easily and effectively. The FX25 can also be used with a silent fan, which is suitable for a variety of small hidden installation environments where ventilation is needed.