Firstly，we can see the difference is that M2000 can monitor the gases CO2, but LKC1000S+ can not. I have listed the difference in the following picture. I believe that you will find out the best model to meet your requirement.
Gases such as alcohols, carbon monoxide, and hydrogen sulfide may interfere with the testing of the sensor. Keep away from alcohol, cigarettes (including carbon monoxide), soot (including acrolein), and fruits (including ethanol) before testing. If the detector is exposed to high-concentration air pollutants environment,which will damage the sensor and make it work improperly. Under these conditions, please place the detector in a well-ventilated place for 6 hours again.
Because the air does not circulate during storage and transportation, in order to achieve the best performance of the device, it needs to be placed in the outdoor ventilation for at least 6 hours before the first use.Meanwhile, each sensor has individual differences, just like everyone is with different alcohol metabolic ability, so a small number of sensors may require longer ventilation. In this situation,to extend the ventilation time will be advised. If the reading is still not normal, please...