I purchased 2 blue and one red....I cannot see anyone using the green units....to an impaired driver it might appear to be or represent a green light. I put blue in the front and rear tire...and have them on flash mode...passed police vehicles at night without issue...I've even had cars stop for me to cross an intersection when they had the light...I guess at night they must think I'm a bike cop! When I do use the red one, I will put it in the rear tire and take out the blue one.