You can't have enough lights,and of those, the rear lights are the most important!I have three on my back side, two on the bike and one on the helmet,I had a guy come up to me two weeks ago in a resturant and said i passed you a few miles back and when i came up over the hill, i thought the sherrif had someone pulled over! (thats what i want all of them to think) so everything works good!Somebody's hood ornament i don't want to be!I run my rear lights in the daytime too! Whats a few battries???to save my bacon?