Features: Different ring sizes to suit different thicknesses. 10mm ring diameter can hold 30 sheets paper. With this binding ring, the paper can be combined at will, the inner page can be flipped, and can be increased or decreased at will. The mushroom hole ring can be used for A7, A6, A5, A4, B5 papers of various sizes, notebook can be folded at 360 degrees. It is also very tight and firm in use and will not fall easily. This is a good choice for everyday notebook binding. The use of this product may also require a mushroom hole puncher, it can punch paper and then bind the paper with these ring. The binding rings can be used with TO NOTE notebook, add sheets to your TO NOTE, very convenient to use. Perfect for students, office workers, travelers, designer, etc.