... opening match hook mouth 2.O China Ring Binder Mechanism,File Folder P123 02 25R/20 Material: metal1. Surface treatment: nickel electroplating ... , 158mm, 171mm, 195mm, 210mm, 241, 264mm, 280mm, 285mm, 292mm, 384mm4. Inside diameter: 15mm, 16mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm ... and common products7. OEM service provided. China Ring Binder Mechanism,File Folder P123 25R/20