DT-1‘s world-class foam technology delivers maximum airflow while maintaining critical engine protectionDT-1 Air Filters come standard or pre-oiledAll DT-1 Air Filters are handmade manufactured in Belgium and USA with the highest quality bonded dual and triple foam availableThe pre-oiled filters are oiled with the highest quality flame resistant bio-degrable filter oilTheir Super Seal base eliminates the need for grease and creates the cleanest and best seal on the market