Suitable for 40mm x 40mm PC Case Fans. YIMATEECO Dust Filter 40mm. 2 x Black 40 40mm Plastic Fan Filter Grills. 💡【DUSTPROOF & VENTILATION】PC fan dustproof filter has a powerful dustproof ability, which can not only block dust, but also not limit the airflow to ensure sufficient ventilation and keep the computer and certain components clean, thereby extending its working life.
eBay