If you are referring to the headphones, it can be any color.
Ultimate Ears headphones come in just about any color you can find in this universe. Everything from white to black to blue and yellow. They even have glow in the dark headphones.
Green
purple
Audio Headphones that are highly rated are Beat Headphones for their ability to cancel out surrounding noise and that they come in different color options.
Yes, iPod headphones work in Blackberries, any headphones will work with a Blackberry.
Regular headphones would do. Headphones that say you can listen to them on a run is a lie, because you can do that with almost any set of headphones, I do when I go on walks.
Presumably, you are referring to polarization. This has nothing to do with the color of light. Light of any color can be polarized, or non-polarized.
At this current time there are no recalls listed for kids headphones. Usually the store that sells the headphones will have info on any recalls. You can check directly with the manufacturer if you have any concerns.
No, black is not a color when referring to light. It is merely the absence of light.
Every standard set of headphones can be used with any ipod.
Beats by Dr. Dre headphones and earphones will work with any device that any other headphones and earphones would work with.
I have an iPod Nano (5th generation) and it can play without headphones, as long as you don't plug the headphones in after you charge it.