What does “Power Saving Function” mean? Sandra Salvatore June 19, 2018 03:49 Updated Follow With 10% power or less, lights will automatically switch to lowest lumen output. Related articles What is COB? What is Lumen? What does “Memory Function” mean? Are Kryptonite front and rear lights waterproof? I have the Street F135/R14. What does the F and R mean? Comments 0 comments Please sign in to leave a comment.