Needing to test various UV light sources, I purchased the General Tool UV513AB Digital UVAB Meter to provide a greater level of accuracy and precision than a personal UV meter intended for consumers. While I have generally been content with this instrument, the name of the meter is a bit of a misnomer as it is truly a UVA meter calibrated for 365nm, which is well outside the UVB range. Sensitivity drops off significantly in a somewhat asymmetric distribution about 365nm, reaching zero % sensitivity at 280nm and 420nm. An important UVB wavelength - 308 nm - has a spectral sensitivity of only 30%. There is no setting, adjustment or filter to obtain a better measurement of UVB wavelengths. It is some difficult to objectively review and rate such a device because its well and not-so-well understood limitations can be attributed to its modest price. Other laboratory grade UV meters can cost more than three times as much and beyond. So, it is the value and utility that must be discussed. Compared to a personal UV meter such as the Oregon Scientific EB612 Personal UV Monitor, this instrument is quite a powerful tool that is easily worth five times as much. The General Tool UV513AB allows for real time UV measurements in a value that can be interpreted on an absolute scale in universal metrics of mw/cm^2 - not an ambiguous continuum meaningful only to the instrument such as relative intensity of 1 - 20. This is especially helpful when observing the output of UV LEDs whose output can vary based on temperature. There are some deficits that are inexcusable, even at its low price point. Despite being a relatively simple device, the menu navigation is oddly confusing. The manufacturer should have added an additional button or switch to avoid the need to cycle through different functions. It is nice, however, that there are two readouts, including one that is able to show min, max, and average values. The meter also has a data store capability that can be displayed on the secondary reading while the main function is still being displayed. The manual for this meter is poorly written. One of my big concerns is that at least one of the specifications is incorrect. The "High Illumination" spectral range is listed at 0.01 mw/cm^2 to 40.00 mw/cm^2. Yet, I have exceeded 40 mw/cm^2 numerous times, reaching up to 66 mw/cm^2. Given that an almost identical meter is sold by Sper Scientific, my guess is that General Instrument didn't make or design this product. Hence, the manual was probably written by someone else other than the designer or manufacturer. Regarding the fundamental capabilities of the sensor, the 40 mw/cm^2 maximum value is well below the output of many light sources, including UV lasers and high brightness LED modules. Just for reference, readings of greater than 8.5 mw/cm^2 can be reached at the sun's maximum intensity during the day in the Midwestern United States. Like the wavelength sensitivity limitation, the maximum intensity ceiling could be addressed with different filters, which can often be extremely expensive. It would be helpful if General Tool could provide easily attachable and modestly priced filters including bandpass variants to address the wavelength and max intensity issues. Despite all of the limitations, this instrument is a good value - especially when compared to what is offered in the larger scientific instrument market. For example, a small bandpass UV filter used to obtain a better reading on a specific UVB wavelength could cost several hundred dollars from a supplier such as Edmunds Scientific. I would have appreciated a few additional capabilities but the price would be expected to increase dramatically. That being said, this instrument is a solid four stars compared to what is available at both lower and higher price points. Pros Inexpensive Flexible sensor mounting/use with wand High level of precision in the microwatts and reported accuracy of 4% Portable Easy to understanding readings Min, max, average readings with data store Cons Poorly written manual Complex function navigation