The Fortune BL-A7 6″ Battery-Operated Portable UV Blacklight contains a 4-watt bulb that emits long-wave ultraviolet light at 365 nanometers. This handheld light can be used to detect invisible ink, authenticate paper currency, check for pet stains, look for manufacturing defects, find insects, or perform similar tasks. It is also great for using with Glo Germ products or hunting for scorpions, which will fluoresce under UV light. The attached strap can be looped around a hand or wrist for carrying. This black light measures 6.5″ long and 1.6″ wide, and requires 4 AA batteries (sold separately). 4-watt UV bulb is approx. 5″ long.