k-ruler only measures pixels and '%', screen ruler does this and cms, inches, picas, points. Has more functionality than k-ruler.
Excellent utility! If you want to change the opacity of the ruler, close the ruler and open the saved settings file (.config/screenruler/settings.yml) and change the value (opacity: 0.8)
Perfecta aplicación, se ajusta bien a los márgenes de la pantalla y tiene gran cantidad de medidas.