First of all, these dividers are exactly 5 1/2" x 8 1/2", which shows a nice attention to detail. Second, the holes are punched at exactly 2 3/4" on center, which is crucial for anything that is going to go into a standard 5 1/2" x 8 1/2" notebook. On the punched side, there is a 1/2" strip of a copper-colored material as reinforcing. It's probably plastic, but it looks like copper foil, and that gives the user additional confidence. On the tab side, there is a tab on each page, each one being 1/5 of a page, which works out well for a set of five. They are as sturdy as any I have ever seen. Also included are a couple of sheets of pre-perforated heavy (0.008", more than double the 0.0035" of typical copy paper) inserts for the tabs. There are also instructions for how to download a template for your computer to print on them, but I was raised by wolves, so I just wrote on them with a pen. They work just fine. In summary, these are excellent 5 1/2" x 8 1/2" five-tab dividers for a 3-ring binder.