UV light is used to detect counterfeit currency and provide access control at bars, concerts and events. UV light can assist in the repair of automotive air conditioner, oil, and sunroof leaks. Crime scene investigators use it to see blood and bodily fluids during investigations. UV LED flashlights are also helpful in detecting repairs in paintings and rugs and are frequently used to detect rodent urine in warehouses. That makes it a handy tool for hotel cleaning crews and professional cleaners as well.