Pretty much crap peak level readings
351061
I just had PG&E come in to do a complete carbon monoxide inspection since my oven was giving off lots of CO. The inspector came in with a top-of-the-line industrial CO detector. After tuning the oven, we ran some benchmarks. So, after the oven is turned on for several minutes, the ambient reading came up to 17 ppm. In the flue, it was over 200 ppm. We had to go outside until the reading would go back to zero. We ran several more tests, and all came back 17 ppm ambient with the windows closed, etc... The Kidde Nighthawk, however, read zero. Which is to be expected. HOWEVER, when I did a reset on the unit and then checked the peak level, it would always show some random level of 25 to 27. It even does this when I go outside to the street and reset the monitor. I've read other people on here have noticed the same thing. To the credit of the Nighthawk, it did register readings above 30 ppm in my kitchen before the PG&E inspector tuned the oven. Was it accurate? I can't actually say. Although, Consumer Reports have done a lot of tests with it and found it reliable and accurate. So, who knows? What I do know is that for peak level testing below 30 ppm, it is DEFINITELY not accurate at all. And that's the biggest concern for me. My wife and I have been exposed to low levels of CO for the past 3 years. Anything above 10 ppm is too much, and according to the PG&E guy, even sustained 17 ppm is not good.

You guys should do more research into this stuff before buying. I'm now shopping around for a CO that can detect low levels of CO.
3006686
Voltage measuring line was outputting over 6 volts which is out of spec.  Unusable.
3923116
I didn't have very high expectations, just wanted a somewhat reliable reading on the outdoor temp.  However, the sensor for this one varies wildly, and Ive tried a few different mounting locations outside, all within about 20 feet of the display unit indoors.  Ive had readings of 98F on 50F days, and moved the sensor w/ same readout.  The main unit display is very dim as well, hard to read.  Maybe there's an adjustment I just haven't found.  Anyhow, this is not a quality unit in any way.
1087460
The only reason it gets one star is you cannot choose ZERO stars!  Inaccurate!  Even dangerous.

I haul a lot of heavy stuff, such as scuba tanks (Hobby1) and lots of plywood and wood for woodworking (Hobby2) and concrete, stone, and more wood for Home Improvements (Hobby3).  I air up my tires according to the Tire Manufacturing specs.  My tires' max pressure is 41, so I keep my tires at 45 due to the often-heavy loads.  Being rather particular about the maintenance of my vehicle, I believed this would be a quick and easy way to see when my tires need topped off.

WRONG!  Filled up to 45 psi exactly, according to three different air gages - two digital and one mechanical, with an error of + / - .25psi (they read to .5 psi), all four of the tire pressure gauge caps read 1/2 red & 1/2 green at 45 psi.  Straight out of the package, they show 1/4 green and 3/4 red.  To test them, I had to fill my tire to 57psi to get them to show all green!

That is very dangerous!  What one would expect is for them to show all-green at 45psi.  This makes these devices totally worthless, potentially dangerous in that someone unknowing would continue to fill a tire until it shows all green --- DO NOT BUY.
4286087
Garbage.  Put it in my basement.  We had a mitigation system installed last year after getting a reading of 4.2.  Tested after mitigation at 2.2.  This started at 3.7 and climbed to 4.5 within a week.  Finally settled at 4.2 and stayed there.  Made my wife and I nervous since we have a 2 year old and another one on the way.  Plans on calling the mitigation company and raising hell made.  Hours spent researching the effects of radon and other mitigation options.  Tested our basement twice with  charcoal test kits as a sanity check and came back 2.2 each time.  Either 3 charcoal tests are wrong or this machine is wrong.  Much undo worrying and stress caused by a piece of equipment that does not work.  I plan on getting my money back.
PS, The charcoal tests were done 12" away from this machine.  Done 2 weeks apart with completely different weather conditions.
871233
Unreliable readings. Stays at 80 degrees even if the room temperature is in the high 60's.
1971647
I didn't expect scientific-instrument precision from an inexpensive hygrometer like this. But this one was so far off as to be useless. I have 3 other hygrometers, and bought this for the dewpoint reading (which it estimates from temperature and % humidity). At a point when my other meters were all reading near 60% (71 deg F temperature), this one was showing 72% humidity.

I returned it as defective.
350507
Honestly, I really regret buying this. The accuracy of pretty much everything is ridiculous. The temperature NEVER reads correctly. The altimeter changes from -60 below sea level to 300 ft above (actual is 7). On my 10 mile runs (measured by the park service as well as other running clubs that run the same trail), this watch has read as much as 13 miles. I don't expect perfection with these readings at all.... but an additional 3 miles on a run is pathetic. I have heard that the Fenix 3 didn't improve much so I will be looking at suunto as a replacement for this.
2931577
This thermometer will not give an accurate reading, or even a steady one for that matter. While testing it, it jumped around and gave us about 30 different readings in a period of approximately two minutes, with a variance of as much as 30 degrees. We will definitely be returning this item.
1280365
We had the NYC Department of Environmental Protection come out to our apartment because we were highly concerned about the EMF's in our kitchen, as indicated by the Trifield 100XE meter we just bought. Their professional equipment proved this meter to be entirely inaccurate, and more like a joke. We looked so amateur with our little meter and felt bad we brought the guys out based on a reading from a cheap device. Better safe than sorry, but it certainly would have abated our concerns from the start had the meter been accurate. We could have received a faulty meter, but there was no way of knowing until the professionals came to prove otherwise. We are sending it back, but evidently we will not get a full refund because it is outside 30 days.
1336750
Very inaccurate.  Reads extremely high compared to Salt system and Pool service company.
2692513
The oxygen saturation feature is a gimmick only; it is completely inaccurate, at least over any physiologically meaningful range. It will not report any number below 95% (I've tested this at high altitude against actual SpO2 monitors). Feel quite cheated.
2277089
So when the price is too good to be true.................well.............um.  So capacitance barely works--reads in pF and compared to my actual stand alone capacitance tester this ennoLogic DMM is out of calibration pretty severely.  First it takes way too long to read a electrolytic over 20uF--a pretty standard value.  Then anything over 60uF it won't read without bouncing all over the place between mF and uF.  I put it on a 100uF brand new cap that tested out perfectly on my stand-alone capacitance meter and it read it 5-uf low.  With mF caps plan on moving the decimal points if it even reads it.  Resistance reading was off by 7%.  There is no back light.  I have not even checked high voltage or low current or much else after finding its resistance and capacitance calibrations are horrible out of even reasonable usability specs.  A shame--I did a lot of searching for an alternative meter to my Fluke which finally went down after years of hard abuse.  I was considering this meter as a back up or additional in-circuit meter to calibrate circuits with multiple meters for real time monitoring but I don't trust this meter based on just the two very basic tests I put it through.  I read all the reviews, and this jives with the many reviews of mine Amazon either didn't post or deleted in its censorship to sell its customer's products--this had a great rating and I can see why now.  Once I put this in circuit and under load I will write more then.  So far--I'd spend the money on a Fluke--this nonsense out of China just isn't worth the wasted money over and over and over again.  You get what you pay for that's for sure.
3599586
I thought this was a full range checker like the ones I have had over past years.  I was sad to find out that it only goes to 6.0.  I wasn't even aware that strips were made that didn't at least check the number 7 - 8 ph that urine should be.  I will never buy this product again.  I realize it was my fault not to have noticed that range is only up to 6.0.  I see no purpose in even having this strip checker as it doesn't even check safe ph which is 7 - 8 ph.
87129
I purchased this in the hopes of being able to measure the noise level in my house before and after installing double pane windows. It allowed me to see that there was 8-9dbA reduction on average (depending on location).

This brings me to the pain point. This device has no averaging capability, which would be required to do a proper comparison. It does have a "maximum" value function, but that's nearly useless unless you're willing to not move around or breathe.

The LCD display is incredibly slow (i.e., you can see each LED segment being updated), and it has very poor viewing angles, but then again, at this price, I can't really complain.
1360234
I can't figure out how to use this stupid thing other than watching it give milli-Sieverts per hour. It stores last CPM and you have to reset the dumb thing to get another count. FURTHERMORE, no directions with this thing and you need to purchase software separately to use real functions. Basically, this thing lets you know what the background radiation is.

Also, the meter jumps about second by second. It makes no sense that mSv per hour would bounce 3-6 second by second when not moved.
71274
This has got to be one of the worst instruction sheets I have ever tried
to follow.
According to the instruction sheet, there are two locations for the input jacks:
at the top (just below the readout) and at the bottom (where they really are).
The instructions also say to zero the unit out, and this only works on the lower pF side (which is very touchy), as when you dial in the uF side, it is always at 000.
The instructions say to insert the black sensor into the jack with the "-" signal, and the red,
with the "+" THEY DON'T EXIST! After brute force logic kicked in, I ended up assuming that the middle jack was negative, and that the left and right were for uF and pF respectively, even though
I was able to get good readings on (4) 50uF and 55uF run caps that showed values from 48uF to 52uF by inserting the black and red tester cables into any combination that included the center connector;  all three are marked as Cx.
While this tester did what I wanted it to do (at least on the uF side), it will take you some fiddling around to get to where you want to go with it, as you might as well just toss the so-called instructions, and just go by your past experience.