EVO TECH front sprockets are dilled to reduce overall weight Made of case hardened steel - Aprilia RS 660 (2021, 2024, 2022, 2023); Aprilia Tuono 660 Factory (2022, 2023, 2024); Aprilia Tuono 660 (2021, 2023, 2024, 2022); Aprilia RS 660 Limited (2022); Aprilia RS 660 Extrema (2023, 2024)