What does the X mean on the light? Donna Post October 27, 2016 19:48 Updated Design feature-helps show where the on/off button is. It is also how to adjust through the different modes Related articles I have the Street F135/R14. What does the F and R mean? Riding with the Lights Are Kryptonite front and rear lights waterproof? How do I know if I’m covered by warranty? Intelligent Features/Modes Comments 0 comments Article is closed for comments.