Twin Air Powerflow Backfire Pre Oiled Air Filter Kawasaki Kx250F / Kx450F The product is a pre-oiled, backfire-resistant air filter specifically designed for utilization in Twin Air Powerflow Kits. It is meant to serve as a replacement, assuring the user of its reliability and performative abilities. Features: Backfire-resistant foam layer laminated to the inside offilter Allows you to eliminate the restrictive stock backfire screen attached to the stock filter cage Pre oiled Sold individually