BOOK DARTS ARE PRECISION CUT, paper-thin metal line markers that attach easily to any page and won’t leave a lasting mark. Use again and again for a lifetime. Eliminate: Bent corners, Paper clips, Underlining, Highlighting, “Sticky Papers” (and sticky pages). An elegant alternative to highlighting, underlining, and folding page corners, these metal line markers are just the thing for students who need to keep their books in good condition for re-use or resale.