I looked at these, but could not justify the price. AOSafety has come out with a similar but cheaper (in more ways than one) product, costs around $13 ea.

I picked up one, and think I will wind up with a set of 4 in the truck. It only has steady and blink modes, but it does have strong magnets on it so you can stick it on the side of your vehicle. It has LEDs out the side and top, so it'll work either way.

http://www2.northerntool.com/product-1/200326738.htm