TaoTronics Black Light, 51 LEDs UV Blacklight Flashlight gave mixed and confusing results for us. Instructions say it only detects dried pee which is hard to detect without out a UV light.. That's OK - we have a puppy that has urinated everywhere on our fine textured vinyl floor planks. We are constantly mopping up pools of pee which are very hard to see even when wet but really stink our unit. The light detects some dried patches or stains but with very limited success. We use the light in the dark with good batteries and with or without the UV glasses. The most we can see is a very faint glow from small patches on floor around its indoor toilet mat - almost like doggy footprints but maybe not. But the light fails to detect other major dry sources of puppy urine. Trust me, if you get down on your hands and knees and sniff the floor in smelly areas you will definitely find the precise area where your puppy has peed - it really stinks but the light fails to show anything. Then after we mop the area the smell disappears. So this is proof the light doesn't work most of the time no matter how close or what angle you shine it. So we are mainly disappointed with the lights effectiveness. The light does illuminate fluff and other floor debris very brightly especially after we used some types of floor cleaner - probably due to phosphorous content in the detergent getting absorbed by the dirt or fluff. The effectiveness of the light for finding pee stains on hard flooring and ceramic tiles is very poor. Maybe it only works on carpet - but we moved our mats into rooms the dog can't access before we got the puppy - just as well we did this. Not impressed.