service and delivery great. Product works as descibed
I have not tool to measure the wavelength, but comparing to my cheap 12-LED UV flashlight, I am able to see different (and more) fluolescnece than the cheap one. Thus I am sure it gives off shorter wavelength UV than cheap one (stated as 395nm).
By naked-eye, or on non-fluolescent white object, somehow the light looks dim white. The "white" light makes it difficult to see weak fluolescent. Voltage/Current (Measuread between inner coil and outer coil of drop-in) = 3.6V/0.06A, 3.8V/0.11A, 4.2V/0.28A.
The emitter is not well centered but not really a con.
Body itself is very nice compared to other "WF-501B"s I have.
In summary, price is slightly high, but it is very nice, short wavelength UV flashlight.