I have the wheel rate compared now for almost 2 weeks and now with various other devices. It was also a borrowed Gamma Scout, a Radex 1503 and my old FH40T from ebay. Large deviations in various test spotlights were there not recorded. Even in a developed Am-241 source (alpha emitters with low low-energy gamma share) an unambiguous reaction of the placed wheel rate with about 100 pulses per minute was observed. The supplied uranium glass making as indicated by the 50 pulses per minute, when you hang up the sensor window directly. Secure the wheel rate is not a professional tool, but for quick verification of goods or as a personal safety monitor, it is ideally suited. Button and off you go without long Herumgeklicke in any complicated menus. The price speaks to the long battery life of course for themselves. I, as an interested layman, am anyway satisfied with the device, it can recommend and awarded 5 stars.