The Knog Boomer is one of the slickest head lights out there. It attaches to your handlebars using it's stretchy body.  The super-bright LED puts out 50 lumens of light.  It has four modes: constant, strobe, fast flash, and random strobe. It's bright, lasts long, looks good, and is easy on easy off, all at an affordable price.  

 

  Uses 2 AAA batteries (included).