A small LED flashlight kept in a pocket is a great backup light if you need it. LED flashlights rated at 1 to 40 lumens generally only have one CR123A, one AA or one AAA battery and the runs times are usually in the two to three hour range. Small and concealable, 40 lumen and lower, LED flashlights are handy tools to have when you need just a small amount of light and space is a concern.