I love these lights.  They are really bright.  It comes with a controller that has a button you can touch for 100% brightness, or 50% brightness.  It also has a button to adjust the brightness up or down, if you don't like it at the 50% or 100%. The controller also has a timer so you can select how long the lights stays on.  On the light itself, in the front there is a button you push to turn it on or off.  On the back there is a battery compartment.  It is really easy to access and does not require any screw drivers.  It comes with batteries already in it.  You just have to pull out the paper to get it to work.  It also comes with 2 sided stick tape and screws for easy hanging.  I would highly recommend this for any one looking for a nice bright light.