Twin Air 151009X Pre-Oiled Dual Foam Air Filter Pre-oiled filter is ready to go right out of the box, saving time and hassle, all while being designed to increase airflow while ensuring the highest level of protection from dirt/dust Dual foam design; 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 Thick, flat foam, greaseless sealing ring ensures maximum contact with your air box, while acting as a breathable gasket for increased air passage Fused outer and inner elements prevent dirt and grime from being lodged between layers while the exclusively formulated adhesive ensures glue seams will not break down