Mass-radius diagram of small exoplanets with precise densities (σ_M/M ≤ 25% and σ_R/R ≤ 8%) from the PlanetS catalog (Otegi et al. 2020; Parc et al. 2024). The red stars correspond to known small planets (R < 4 R_⊕), with precise radius and mass measurements, that have a hot or warm Jupiter companion (R > 0.8 R_Jup). Orange dots are planets in multi-planet system of all kinds. Gray dots are planets in singleplanet system. Composition lines are displayed for pure-iron (brown) and Earth-like planets (light-brown).