This is a Geiger counter module from DFRobot. The module has a Geiger-Müller counter tube type M4011. This can be used to measure alpha, beta and gamma rays. A Geiger-Müller counter tube detects when an ion pair is created by incoming radiation. This is then expressed in CPM (counts per minute). Normal ambient radiation from the sun, natural uranium, radon, certain types of stone such as granite, plants and animals can be anywhere from about 5 to 60 or more CPM. A Geiger counter only measures the number of ion pairs created per minute. The CPM can then be converted into µSv/h (sievert). It cannot distinguish between radiation type and energy. This is not a professional measuring device and should not be used as a guarantee of your own safety. The module has a buzzer that sounds the frequency of the CPM count. With a gravity connector, the module can be connected to a 3.3V or 5V microcontroller such as Arduino or ESP.

Attention: The Geiger tube is operated with a voltage of up to 400V. After switching on, do not touch the high-voltage circuit near the positive terminal of the Geiger tube.

Features:
Type M4011 Geiger-Müller counter tube.
Alpha, beta, gamma radiation in counts per minute
3.3V/5V logic compatible
Gravity connection
Buzzer for acoustic feedback

DFRobot Wiki
Technical Details:
Manufacturer: DFRobot
Manufacturer SKU: SEN0463
Input voltage: 3.3V/5V
Working voltage: 380V-450V
Max measuring range: 1200 µSv/h (theoretical value)
CPM ratio: 153.8CPM/(µSv/h)
Dimension: 107 x 42 x 22 mm
Weight: 71.5g

Scope of delivery:
1x Gravity Geiger counter meter for ionised radiation.
1x 30cm Gravity 3pin digital sensor cable PH2.0 to XH2.54.