For 2017 - 2020 KTM 390 Duke. For 2020 - 2021 KTM 390 Adventure. For 2017 - 2021 KTM 125 Duke. For 2021 KTM 200 Duke. For 2017 - 2019 KTM 250 Duke. For 2021 KTM 250 Adventure. Thus allowing engines to breathe better as compared to the inconsistent airflow of cotton/foam filter.