The Sonel MRU-21 is an earth resistance meter based on the 3-pole measurement system. The MRU-21 features automatic compensation for the used test leads. In addition, it is possible to adjust the maximum measuring voltage. This meter can be carried around the neck and features soft-touch buttons for easy use. A big multifunctional LCD display shows the results and explains the necessary user inputs. All functions are easy accessible and customizable with the soft-touch buttons through the built-in menu.