For those of you that use lights on your spokes for side visibility, what color do you use?

This link is for SpokeLits (they come in green and red)...
http://www.night-gear.com/p/Illumina...y-Nite-Ize.htm

I know that normally front and back lights follow suit like a car: red in the back, white in the front.

Just curious is there was a preferred standard for side lighting.

TYIA!