When evaluating a 100 LED UV flashlight, the most critical factor is the wavelength, typically measured in nanometers (nm). For most industrial and commercial uses, 395nm is standard for detecting pet stains and scorpions, while 365nm is superior for forensic analysis and counterfeit detection. You must also verify the LED quality and lifespan, ensuring they are rated for at least 50,000 hours. Additionally, check the housing material; high-grade aerospace aluminum alloy with Type III hard-anodized finish is preferred for durability and heat dissipation.