efficiency filtration: The filter cotton material effectively captures dust, pollen and airborne impurities, helping maintain a clean indoor environment and improving overall air quality. compatibility: Designed to fit most standard air conditioners, including models from various brands. These 21*52mm filter pads install seamlessly to ensure airflow and cooling performance without restricting your unit's operation. Long lasting construction: Made from quality cotton materials that resist wear and tear, these replacement pads provide reliable service life and help prevent debris buildup that can compromise your air conditioner's efficiency and longevity. Easy maintenance solution: Simple installation requires no special tools or technical knowledge. Just remove the old filter and insert these replacement pads for an immediate improvement in your cooling system's operation. Use in home or apartment air conditioners to improve indoor air quality and reduce dust and pollen exposure. Use in offices or small commercial spaces with standard AC units to maintain airflow and cooling efficiency. Use in dorm rooms or shared living spaces to minimize dust and pollen exposure while staying comfortable.