Hi!

Is it always yellow?

The vast majority of the ones I have seen are yellow. I suppose this
is the cheapest and therefore most popular color. Most people are
probably never going to look or care all that much. :-)

That said, I have seen some red ones, purple ones and some orange
ones. Something in the back of my mind wants me to say that I've seen
dark brown ones as well, but I'm not sure if that's right.

William