Our plastic loose leaf ring is 28 mm in inner diameter. It is recommended that the binding thickness should not 28 mm. 6 different bright colors are available, include blue, red, green, yellow, orange and purple, different colors not only can satisfy your multiple needs, also can help you classify documents according to different colors Feature - ColorAssorted Color - Material: Plastic. - Size: 3.50X3.50X0.40cm/1.38X1.38X0.16 inch. - Inner diameter: 28mm/1.1 inch. - Tight lock-in design: Multi-color paper leaf binder rings, tight lock design makes your books organized, not scattered after , easy to operate. - Occasions: Suitable for binders, study or note cards, classroom, office, home; Fastening any size document stack and keys and . - Package includes 100pcs rings, contains 6 different colors. Enough quantity for home use and office use, also suit for children learning use. - Made of plastic material, double holes to keep sturdy and . - These rings are two holes to fix in, not like other metal rings, without any strength they can be easily install. Will not hurt your hands or children's hands. Package list: loose-leaf rings