This product uses a Geiger-Miller counter.Counter for detecting the intensity of ionizing radiation (beta particles, gamma rays and x-rays).Use a gas tube or a small chamber as a probe.When the voltage applied to the probe reaches a certain range.Each time the ray is ionized in the tube to produce a pair of ions, it can be amplified to produce an electric pulse of the same size.And recorded by the connected electronic device.The number of rays per unit time thus measured.The alarm threshold measurement rate can be arbitrarily selected.