ZWB2 Ultraviolet Filter for Flashlight Diameter 20.5mm 28mm 41.5mm 50mm?

Good item, for people who knows the idea of UV filtering. What I bought is 50mm for my big flashlight UV light.

I have several other long wave UV filters (at much higher prices) and they do not seem to work better than these.
These units cut out most of the visible light from high power UV LED's and show the true color of my minerals very well.
Like all UV filters these reduce the amount of UV light from the source, but the loss is hardly noticeable.
Thank Dankung.

It took 12 days arriving here. This product is a perfect bandpass filter. That is, it lets through the 365nM UV B and blocks almost all visible light (it is a very good match for the UV LED). This is great for observing fluorescence - minerals, dyes, scorpions, glue, etc. Without a filter these diodes produce a lot of visible light that washes out too much fluorescence.
The filter makes the my flashlight(from Dankung too) UV light much more useful.

Very fast delivery. The ZWB2 has greater transmittance at the LED's peak emission frequency and will actually allow more UV light through. Thank DANKUNG for multiple diameter options. I searched the whole internet only found 4cm filter here.