直径3cmと表記がありますが、届いた商品は2cmでした。ページ誤表記なのか、商品の誤出荷なのかわかりませんが残念でした。

Di. R ringe sind nicht passend zu meinen notizbuechern. Behalte die Ware trotzdem falls spaeter gebraucht.Sonst alles OK.

I love these. Very easy to install, and a lot bigger than I expected them to be. Their perfect for my notebook.

I purchased this to switch out the 20mm rings on one of my binders to larger rings, so it can hold more notes. It's worked perfectly!Luckily, the old one was easily unscrewed, making the conversion a breeze. These mechanisms are well made, thick & sturdy, with end tabs that open with ease.If you're looking to convert an old portfolio into a planner/binder for the first time -which I've also done- it's not difficult. You'll simply need to 'punch' holes through the cover—which can easily be done with little effort. If you don't have a workbench, you can use a piece of wood, old shelving, or a thick flattened Amazon box as a work surface to stop the hole you'll punch from breaking through to ruin what's below.Place the mechanism at the inside middle of your portfolio WHERE you wish to affix it, then either hammer a nail, or, drill through the two holes...being careful not to punch past your work surface. I've used a drill & TWO screws, so the holes align perfectly.All you need to do afterwards is flip the case over, push the ends of the smooth screw 'caps' through the holes from the outside, place the mechanism directly over them, then use a wide flathead screwdriver to fasten the mechanism securely in place.

Works, makes nice books see picture.