These are amazing dividers that have helped signal where books are within our children's collection. The plastic is very sturdy and the sleeves to add letters / call numbers / or book types are great too. The only drawback to using them as shelf labels is that they only have inserts on one side. It would be great if they had a card holder for each side. We ordered one to mark divisions in our beginning readers that are separated by level and to show where each dewey section begins in our nonfiction. It has really helped us to find books more quickly and to point out collections to library users. We ordered more and put letters on these dividers as well in our picture book section. Staff also love them.