Lunarlipes Carbon Monoxide Detectors, Portable CO Detector with Temperature Sensor ＆ LCD Backlight Screen, Handheld Carbon Monoxide Meter Tester 0-1000PPM Range, Indoor/Oudoor (Includes Battery x3)

Works fast, it's accurate.

machine payed for itself -would have cost me a service call at the furnace company @ 150

I think everyone needs this at home and while traveling camping etc. trip earlier this year one hotel read at zero other was at 6 made me aware so I was able to crack the window and alert the front desk that carbon Monozide in low levels was in that room! Peace of mind for a small amount!

Good battery life, it lasted 4+ days on the original cells. Alarm set point is adjustable which is good. It correlated with the gas furnace inspector's readings within acceptable limits. I did not have time to give it an actual calibration verification run. I really wanted a data logger but that added an extra $100 or more to any unit available. I'm a retired Control Systems Engineer so I am familiar with the measurements involved. It takes a minute for it to register a reading so be patient with it. Good bang for the buck.

Overall, I'm impressed with the quality of this $40 carbon monoxide meter. Well worth the expenditure to check for appliance leaks in the house, as well as the cabin of my vehicles.The instructions are not clear on the calibration time, as many questioners noted. When first turned on, the digital screen will display "120", and begin to count down each second, until 2 minutes later, the display will automatically change to the sampling mode. The 120 second calibration mode can be interrupted at any time by pressing the “ON” button, and will revert to the sampling mode. The instruction sheet lists a 60 second response time; the data sheet for the Nemoto NAP-505 sensor lists a 30 second response time. The response time varies with temperature, and increases with colder temperatures. Your choice if you want to wait the full 2 minutes.The instructions indicate a typical sensor life of 3 years, while the data sheet for the NAP-505 sensor lists an expected life of 7 years. The electrolyte used in the sensor is hygroscopic, and will attract water will degrade the device. Store the CO meter in a low humidity environment, to achieve the expected life.The CO meter in the sampling mode with backlight off, draws about 8 mA. The 750 mAh AAA Eneloops I use (to avoid parasitic cell corrosion/leakage) will therefore power the unit for probably 75-100 hours of realistic “ON” time. I’m satisfied with that amount of operating time….more than I need.I have no way to test the ppm accuracy of the meter, other than to approach the exhaust pipe of my car. The CO concentration does increase the close I come to the pipe. I don’t have a standard gas bottle. The NAP-505 is a quality Japanese sensor, so I’m inclined to trust the accuracy. My gross test on my car shows that the meter does work.It’s great that a product used for safety checks, is available at such a reasonable price. I’d buy this CO meter again.