K&N 17-19 KTM 125 Duke 125 / KTM 250 Duke 249 / KTM 390 Duke 373 Replacement Drop In Air Filter - KT-1217

K&N's high-flow air filters are available as a replacement for your stock motorcycle air filter element. They are custom engineered to fit your specific application and are designed to provide low restriction and increased performance, while providing excellent engine protection for your motorcycle.
Installation Instructions