Features: 1.It is a small disc with raised edges, with which the book can be rotated 360 2.The paper with the hole of the mushroom can be combined at will, and the inner page can be turned over and can be increased or decreased at will. 3.Through the mushroom hole, the inner paper can be turned into different inner pages that can be matched with personal preference. 4.Freely match the ring color, different ring sizes to adapt to different thicknesses 5.It is a good choice for daily notebook binding specification: 1. It is a small disc with raised edges, with which the book can be rotated 360 2. The paper with the hole of the mushroom can be combined at will, and the inner page can be turned over and can be increased or decreased at will. 3. Through the mushroom hole, the inner paper can be turned into different inner pages that can be matched with personal preference. 4. Freely match the ring color, different ring sizes to adapt to different thicknesses 5. It is a good choice for daily notebook binding : Condition: 100% Brand new Mushroom Binding Ring Adapts to Thickness: 10mm can hold 30 sheets of paper 15mm can hold 50 sheets of paper 20mm can hold 80 sheets of paper 25mm can hold 100 sheets of paper (paper is A4 paper thickness) Optional Style: Red 10mm Binding Ring, Yellow 10mm Binding Ring, Blue 10mm Binding Ring, Red 15mm Binding Ring, Blue 15mm Binding Ring, Yellow 15mm Binding Ring, Red 20mm Binding Ring, Yellow 20mm Binding Ring, Blue 20mm Binding Ring, Red 25mm Binding Ring, Yellow 25mm Binding Ring, Blue 25mm Binding Ring Package List: 12 x Mushroom Binding Ring