Amazon.com : BinderRings Magnetic D-Ring Binder Mechanism (25 Pack), 3-Ring Binder 1-inch D-Shaped Rings for Standard Letter Paper (8.5 Inches x 11 Inches), Includes 25 Vinyl Sheet Protectors : Office Products
A4 4 Ring Binder Metal 4 Inch Capacity 100mm Mechanism
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Set of 5 World Wide Ring Binder Mechanism 3 Ring Round .75 inch Diameter Rings | eBay