Rustproof & Long-lasting: These metal binder rings feature a multi-layer nickel-plated finish for rust resistance, strength, and durability. Laser-polished to a smooth finish to prevent hand scratches. Each binder ring supports opening and closing over 10,000 times. Standard Size: The package includes 80 pieces of loose leaf binder rings. Outer diameter: 25mm (1 inch), inner diameter: 20mm (0.8 inch). Each binder ring can hold up to 140 sheets of paper. Easy to Open/Close: Simple to use. Hold the ends with both hands, then push forward with one hand and backward with the other with slight pressure. The rings securely hold flashcards or papers without loosening. Extensive Use: These small binder rings are ideal for loose-leaf binders, flashcards, books, papers, memo filing, keychains, and more. Keep your small items organized. Lock Tight: The movable opening features a secure lock design that stays in place during use, preventing dislocation and keeping papers firmly held even with frequent handling.