Amazon.com : Yoobi 1 Inch Binder Set – 3-Ring Binders with 2 Pockets – Perfect for School or Office – Holds up to 220 Sheets – 4 Pack – Solid Multicolor Variety : Office Products
All About 3-Ring Binders: Types, Features, and How to Choose the Right One | OnTimeSupplies.com
1 in Ring Size - Binders, Round, 3-Ring Binder - 1GEK2|00603 - Grainger