LightFe UV301 365nm & 395nm Violet UV LED Flashlight Fluorescence Sterilization Detection Pen
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Whenever you're looking for a torch, UV-ED, ... you need to go to the 365nm. When visible light is filtered you hardly can make out the visible light. The fluorescent effect is much stronger than with 390 - 400nm LEDs. Some minerals and fluorescent colors need to have the shorter wafelength to show this effect at all. Thre really nice feature is the step up converter in this particular flashlight. It runs from one singe AA battery.
When you want to check out how clean your hotel bed/bathroom is, this is the tool for you. Get ready to be shocked at the amount of detritus exposed by this nifty flashlight. Note - it is the 365nm one that does the trick. I have only been able to make it turn fully on and off - no strobe or half power mode found - but that is no issue for me.