I use one-digit-dollar flashlights when I was very young and haven't used such a stuff for years. I got interested in flashlights worth dozens of dollars because friends around me often talk about them. I wonder why the stuffs are so attractive to my friends, so registered here for some answers. Here is a flashlight i found yesterday , and the following are my questions: 1. What are advantages of LED material. 2. What does 7 LED mean -- is it a slip of pen? 3. From my friends, I know a flashlight's lightness is denominated by lumen, so please talk about it. 4. The product referred accordingly can be charged with DC 12V and then charge some Nokia and Samsung USB devices, but can such a small thing has this capacity? The final question is: why do you spend dozen or even hundreds of dollars on just a flashlight? Thanks in advance.