03-06 YAMAHA KODIAK400: Twin Air ATV Pre-Oiled Air Filter For many years, Twin Air Factory Pre-Oiled filters were only available to top professional race teams and O.E.M. customers. The results were so good that Twin Air now offers the same factory treatment to everyone.Twin Air starts with an Original Dual-Stage Air Filter and completely submerges 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 resealable 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.W