Great tool and toy. Actually I used it more in R&D activities, and recommend it to my colleagues who was also impressed from size and functionality. Probably going to order some more.

Expensive: can't really tell it it works because the light is always on green.

Download the optional software, it graphs a numerical measurement, with high resolution. the software also has the option of recording the data to a file. which I found useful for graphing longer periods for evaluation. Without software all you get is the red/yellow/green light If you want to test if the thing works, get a bottle of nail polish remover, or other suitable VOC source and allow the fumes to waft over the device, this was how I initially tested mine with nail polish remover. For identifying specific contaminants, I think it is unreasonable to expect this device to have that capability. it is small, cheap and does a simple task well. More complex air quality analysis would cost a lot more. Eventually sensor technology advances may render this obsolete by allowing differentiation of contaminants in this kind of package, but this device does what it claims - no muss, no fuss.