Mass-radius diagram based on the TEPcat catalog (Southworth 2011, visited on 10 August 2021). TOI-1201 b is indicated as a red star outlined in black. The gray points represent the other planets (R < 3 R_⊕ and M < 12 M_⊕) with masses and radii measured to precision better than 20%. The red points are those planets around M dwarfs (T_eff <4000 K). All theoretical composition models are taken from Zeng et al. (2019). The lines represent models for cores composed of pure iron (100% Fe), Earth-like composition (32.5% Fe + 67.5% MgSiO₃), pure rock (100% MgSiO₃), and pure water (100% H₂O at 700 K). The area between the solid and dash-dotted lines of the same color represent the theoretical composition models for Earth-like rocky cores with varying sizes of H-He envelopes (0.1, 0.3, and 1%) for equilibrium temperatures of 700 and 1000 K, respectively. The plot is inspired by Van Eylen et al. (2021), though presented here in linear scale to emphasize the mini-Neptune population.