Shake Flashlight

These are a disappointment.  I have yet to find one that is superbly reliable.  The one thing you want is a flashlight that will work when you need it in an emergency and these tend to let you down when you need them.

A better option might be the hand crank version of lights.  I had one of these years ago and it finally failed mechanically.

The reviews on this particular model seem very good though I haven't owned this brand it is probably the one I'd try.  It looks good in Olive Drab too.