I had been looking for months for a very narrow shelf when I found this one.  Lots of places sell shelves 5 inches and wider, this is the first 4" one I found AND it is very attractive!  I bought one earlier at full price.  Now that they are on sale, I'm buying two more.  Despite their narrow width, because they install by sliding over a solid wood ledger that attaches to a stud, they can handle quite a bit of weight.  A real find!