1 HUSQVARNA TE400: Twin Air Air Filter The Twin Air Air Filter&#39;s design, high-quality materials and superior construction deliver unbeatable performance and protection - and make Twin Air Filters the hands-down choice of more World and National Champions than all other filters combined. Twin Air filters are designed to increase airflow while ensuring the highest level of protection from dirt / dust. Coarse open-pore foam catches airborne dirt, grime and sand. Fine open-pore inner foam acts as a second filter to trap the smallest particles while ensuring maximum air passage. Exclusively formulated adhesive ensures glue seams will not break down.