Bests & Worsts Reviews from Amazon

We compared this device to a Ludlum GM counter that was calibrated by Ludlum last week. As you can see from the image, the GQ GMC-320 underestimated the true exposure in mRem/hr by 5-10x. The Ludlum counter is extremely precise and quite expensive. We had hoped that this GMC-320 would come close (even half of the Ludlum's count would've been acceptable). Unfortunately, this device is totally inaccurate. I'd say that the GQ GMC-320 is useful ONLY for qualitatively detecting presence/absence of radiation. I would strongly discourage its use in any quantitative way. If you use this to actually measure radiation exposure, please note that you may be receiving 10x more radiation than you think!