The Uni Air Filter #NU-3226ST is a foam air filter designed for off-road motorcycles, specifically the Yamaha WR250Z 91-97 , YZ250 89-92 2-Stroke, YZ125 89-92, and WR500Z 90-93. It is made in the USA and comes with a foam gasket. This air filter is an essential component of the air intake and fuel delivery system, ensuring that the engine receives clean air for optimal performance.