I bought 2 because I was restricted in having to mount only on exterior of the wall in a totally dark area.  One light was very easy to install but the other light was impossible.  Somehow the screws were somehow damaged so much that they would not unscrew.  I ended up just getting it told hold as long as you do not mess with the base.  The arms do not adjust very well.  But it gives me light.  I could not find anything else.