You should always carry around a small flashlight in your bag or pocket.  It can be a great help when you are in the dark and need some light.  There is a LED microlight that is very small and compact but produces a powerful light.

It comes in a black body and has different colored led lights.  You can find a blue, green, red and white led light.  It has four light functions: high power, low power, strobe and signal mode.  And the signal visibility is up to 1 mile.  It is very easy to replace the batteries in these lights as well.  You can easily clip it in your pocket, belt, bag or anywhere that is very accessible because of the stainless steel universal clip.