GQ GMC-600 Plus Geiger Counter Detector Dosimeter Alpha Beta Gamma XRay LND 7317

You could mention "accuracy", "sheerness" and "thickness"

I have had mine for a few months now. I got it more out of curiosity than anything else. It has performed well and battery life is great. I monitor background and checked out an old Pentax lens I have that I know has a radioactive rear element. A lot older lenses made from the 1940's through the 1970s used thorium oxide. Quite a surprise how much radiation the rear element puts out at it's surface. The lens above measures 250 CPM at the front element and about 130 CPM behind the camera when the lens is mounted on it. Most radiation is gone by the time you get about 3 feet (1 meter) from the lens with reading jsut a little higher than normal background. .

Very sensitive geiger counter works excellent on alpha radiation thanks brian.

Detector works as described, very satisfied

Works great up untill 22k counts then unit starts detecting an unreasonable jump in counts 100k or so and the unit stops responding after removed from the test source still reads. Samples is ore in epoxy sealed in plastic bag, units not contaminated it resets to normal after a restart. Scan the sample again crashes. Not impressed as the unit is rated for 1M counts per minute. I'm not sure if this is normal for the unit but I would hope not. I've reached out to tech support and they have responded, and will be sending me a firmware update. I will report back. Update support has been amazing so far, including sending me a custom firmware update. I didn't work but I am in the process of filing an exchange I'll update when done.