Contrary to some reviews here, the device is not very good and it's not because a misunderstanding of the device.Yes, it's important to set the device to the right refresh speed (5min, 30min, auto, real-time). And yes the device does state a 10% error margin.Regardless of that, the values lag the true values (measured by more advanced devices) by a large margin. Both in update speed and actual values.Im quite disappointed by this device.

Does what it says.... Checks air quality and relative humidity with accuracy. Simple to charge with a standard USB supply. Battery life depends on how many times the unit samples. You get four settings and can get over a month on a single charge with the lowest sample setting. Good quality product and for anyone worried about mould and high humidity levels in their room, you can now check at a glance.

A alguien más le pasa que siempre marca eso, en 3 lugares he estado y solo marca eso, o esta muy bien el ambiente en todos lados o el equipo está mal

Convient bien et mesures cohérentes avec des appareils professionnels que j'ai testé à côté

Com menos de 2 meses de uso, soltou a fumaça mágica enquanto estava recarregando.Não recomendo.

This is reasonably similar in accuracy to government level devices at reasonable levels.I'm writing this review in response to other reviews complaining about things they don't understand.First of all, if you actually read the specifications of the sensor, there is a reasonable margin of error. I've tested this sensor and there is actually a government website that compares Elitech's sensors to government sensors for PM 2.5. It is accurate and within the specified margin of error. Yes, even the same sensors side by side will be slightly different from each other. If you are complaining that it one shows 3 PPM and another shows 5 PPM, then you need to realize that at those levels the margin of error is 5... so being 2 points apart is within the specifications of sensor. And either way, it literallt makes no practical difference; you would still know the air is excellent. The same goes for if one reads 100 PPM and another reads 90, that is also within the margin of error and you would still know the air sucks!Second, there are multiple modes. If you put it on a mode where you make the sensor work every 1.5 seconds, of course the battery is going to be used up faster compared to if it runs every 5 minutes or every 30 minutes.Lastly, if you are complaining that the readings are completely different from each other or that the number doesn't change even if you move to different places... you probably have them refreshing every 5 or 30 minutes and you need to put it om the "R" mode where it refreshes every 1.5 seconds instead if you want instant information.Basically, all the negative reviews are by people who don't understand but think they understand. This device does what it is supposed to and is well engineered. People who complain literally can't read or didn't bother to read about what they were buying.