This exposure meter was purchased to measure the intensity of UV rays outdoors. This gauge seems to be doing the job well. But as others have pointed out, the user guide is too short and doesn't provide enough information on how to use all the features. It should be noted that the meter must be assembled before it can be used. These instructions can be found in the user manual. I could not find any other source of information online on how to use this gauge. I don't have a science or engineering background so I probably won't get the most out of this device. As far as I can tell it measures both UVA and UVB at the same time and there doesn't seem to be a way to measure just one wavelength or the other. Another thing is that the power button is activated too easily. It doesn't take much pressure to turn it on accidentally. It is inconvenient to keep it in a travel bag. However, it could accidentally turn on when carried in a regular daypack. Instead, I would recommend using a switch that needs to be flipped up and down. The product is called "General Tools & Instruments UV513AB Digital UVC Meter" so I assume it measures both UVA and UVB, but then why is it called "UVC Meter"?