Bests & Worsts Reviews from Amazon

I've had this detector for over 3 years now and it's true what they say about it needing calibration every year. This means sending the unit back to the manufacturer for service. If you don't, it tends to sneak up with progressively higher readings. Unfortunately, I found this out after I bought it. So here's the thing you will need to consider: you are paying $130 for 1 year of ballpark accuracy readings. After that it will cost you another $75 (+2 way S&H fee to Michigan) per year just to maintain the same reading accuracy. Seems like a high price to pay when you can have a professional come in yearly and give you a more accurate reading for about the same price. Granted, readings can change daily to weekly but in my three years of measuring, I've found that the detection range was pretty consistent (within 2-2.5 pCi/L seasonal differential). Now I have this $130 device that needs another $100 or so to make it semi-useful again.