ActronAir Air Filter Right suits SWA18/24E is the genuine replacement air filter for SWA18E and SWA24E wall split systems, maintaining the return air filtration that protects the indoor coil from dust and debris accumulation that reduces heat exchange efficiency and airflow. Wall split filters are model-specific -- this right side is matched to the indoor unit housing dimensions and return air grille configuration. Clean or replace at the interval specified in the owner's manual, typically every 4-6 weeks in average conditions. These are genuine model-specific filters -- do not substitute with generic cut-to-size filter media as incorrect thickness alters return air resistance and may dislodge from the filter frame.