YG_Oline 48 Pcs Black Slide Grip Binding Bars, Spine Bars for School Office Report Covers File Holder, A4 Size, 40 Sheets Capacity, 12 Inch

Its just the black plastic edge that holds the paper. I got it for the 2 younger kids who are 6 and 8 they love to write stories and I just trim a chunk off to fit normal copy paper

Used to make dividers for fish tank

When ordering, I did not realise how much longer these binders are, compared to the height of the legal-size paper. This means that, once you slide your booklet into the binder, there is a large portion of the binder protruding at the top/bottom of the booklet, making it look rather odd. You have to trim around three-quarters of an inch, in order to have the binder the same height as the booklet. Other than that, they are pretty good at holding 40-pages paper. I have not yet tested to see how well they hold the sheets. Once I distribute the booklets, I will report back on their durability and strength.