Transmission spectrum metric as a function of the planetary radius for HD 207496 b and other well-characterised small planets. We show all planets from the exoplanet archive with precision in mass and radius better than 50%. The planets with mass derived by RVs are shown as circles and the planets with mass derived by TTVs are shown as squares. The colour of the points indicates the planet effective temperature. HD 207496 b is marked with a box. This graph was created using the mass-radius diagram code (https://github.com/odemangeon/mass-radius_diagram).