Rotation periods against convective turnover time (τ_c) for fast rotators selected from several young open clusters. The sequences show a clear exponential dependence on τ_c. NGC 2281 and M 37 are combined into a single fit. The black lines show cluster-by-cluster exponential fits to the data. The individual open clusters are Pleiades (brown, Rebull et al. 2016), NGC 2516 (purple, Fritzewski et al. 2020), NGC 3532 (orange, Fritzewski et al. 2021b), NGC 2281 (black, this work), M 37 (green, Hartman et al. 2009), and Praesepe (blue, Douglas et al. 2019).