[en] This publication describes the use of a consumer radiometer distributed by the Criirad, sensitive to γ and X rays, and to high energy β particles, and which replaces radiometers previously sold. It first indicates its applications and limitations, and proposes a presentation of the device (overview, cautions). It describes its energy supply, how to put it in and out of operation, how to perform measurements, the position of the Geiger-Muller tube, and additional functionalities. It also gives some basic notions for measurement interpretations: detector principle, what is actually measured, cautions, ambient and contact measurements