I bought these to separate stacks of folded shirts on my closet shelves (so when the piles get high they don't fall over).  They work GREAT and I've ended up also using them in my pantry for holding up paper bags and separating and holding up bags of chips so they're not falling all over.  They're simple to use and very strong - I bought A LOT of these but will probably still be back for more.  :)

Pros: Simple to use with standard shelf thicknesses
Cons: No cons for me.