Our plastic loose leaf ring is 28 mm in inner diameter. It is recommended that the binding thickness should not exceed 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 colorsFeature- Color: Colorful.- 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 collapse, easy to operate.- Occasions: Suitable for binders, study or note cards, classroom, office, home; Fastening any size document stack and keys and swatches.- Package includes 100pcs binder leaf rings, contains 6 different colors. Enough quantity for home use and office use, also suit for children learning use.- Made of good quality plastic material, double holes to keep sturdy and durable. - 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.