What can I say - my concerns were completely unfounded. The small crab is provided on both sides with silicone pads, so that the glasses may be damaged under any circumstances. The light cone of owl is made for the Kindle. He lights up the display from full - without over shoot too much light. If one directs the light in the middle of the display and the Kindle holds absolutely straight before his eyes, although it may actually happen that it appears easy. This problem can, however, easily circumvent that aligns the light beam, for example on the upper right corner of the display and the Kindle holds very slight angle (really minimal, has absolutely nothing unnatural!). Then the display is very nice and evenly illuminated in a pleasant light intensity.
Once plugged in and turned on, you no longer perceive the owl reading. She's really lightweight and falls on the glasses literally of no consequence. When they are attached to the front far enough to the temple, also arise no flicker of light in the corner of my eye.
With the ball joint, the light in every direction imaginable can throw. As a rule, however, no readjustment is necessary when the beam was once aligned correctly - finally, the light cone so the line of sight.
It only remains to be seen whether the battery actually holds the promised 40 hours.
Conclusion: For eyeglass wearers (and we are sooner or later probably all ...) is the owl, the ideal reading light. Strange that not before someone came up with this brilliant idea!