Twin Air Factory Pre-Oiled filters have been available only to top professional race teams and O.E.M. customers. The results have been so good that Twin Air now offers the same factory treatment to everybody. They start with an Original Dual-Stage Air Filter and completely submerge it in BIO Liquid Power Filter Oil. After the filter is massaged to ensure all pores are evenly coated with oil, it's placed in a temperature-controlled room to allow the oil to completely cure. You just open the re-sealable bag and install. The original Dual-Stage Air Filter completely coated in Twin Air's BIO Liquid Power Filter Oil. 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. Thick, flat foam, greaseless sealing ring ensures maximum contact with your airbox, while acting as a breathable gasket for increased air passage. Fused outer and inner elements prevent dirt and grime from being lodged between layers; unlike Twin Air, this can be a problem with inferior two-piece designs. Trapped particles can restrict airflow. And, if dirt works its way into your engine, a pinhead-sized granule will gouge your cylinder, piston and rings like a bullet. Ready to install right out of the box!