I bought this TravelFlex as well as the Mighty Bright Xtraflex 2 LED book light. I liked them both, but I give the edge to the TravelFlex.  Both devices use bright and efficient LED lights.  The light color is a bit blueish (as with all LEDs that I've seen), but both provide plenty of light for reading in the dark (and they double as flashlights in a pinch).  Both devices clip on to the top edge of your book or Kindle and have flexible necks that allow you to position the light in such a way as to illuminate the whole page without glare.