Review on Klein Tools ET110 CO Meter: Carbon Monoxide Tester, Detector & Exposure Limit Alarm - Includes 4 x AAA Batteries & Carry Pouch by Aries Boyce

Overall I like this product and it seems to give reliable readings. But accuracy is sometimes questionable, as some other reviews have noted. First, it definitely seems like there's always a lag of around 20 seconds. I can run with the meter behind my treadmill and after about 15-20 seconds the reading jumps significantly to 20-40ppm. Walking into an open space seems to be a faster reaction. Often less than 10 seconds. I've had a few weird moments registering 0ppm in the garage. It would be impossible. With this device, I came to the odd conclusion that parking lots have terrible air, even if they're outdoors. Walking through a busy mall parking lot I got a jump to 50ppm with this unit, but in my CLOSED garage I never saw a reading above 20ppm. I think thank goodness the HVAC system. I've also experienced some weird moments where the clean air in my home would jump from 0ppm to 3ppm and immediately drop to 0. I wonder what that means? Just a possible "hint” of CO? I also recommend that the engineers who designed this device consider disabling the Max/Average reset button. Just because I want to delete the maximum doesn't mean I want to delete the average. Does it make sense?