My fiance and I were staying in a hotel one night, and we were packing up our stuff for an early check-out the next morning. She knelt down to grab her purse, which was under the desk. When she rose up, she hit her head hard on the corner of the desk. The noise was incredibly loud and she immediately grabbed her head and started crying. I grabbed my Surefire E1E to check for blood, but I didn't see anything. Then I remembered that my Kroma MilSpec flashlight was in my backpack, so I grabbed it and fired up its blue LEDs. Instantly I saw a small pool of blood that was oozing from her head, so I got some ice and made her an icepack. I knew that blue light was supposed to help identify blood, but I'd never seen it in action until now. Even though my fiance has black hair, it was so easy to see the blood under the blue light. Thanks, SureFire.