Loose-leaf rings are round nickel-plated snap hinged rings. These round rings have a locking mechanism that opens to add or subtract materials, yet locks securely once it is closed. The 1/2" are a little difficult to open due to there size so please keep that in mind when ordering. The inside diameter of this loose leaf ring is 1/2”. * Inside diameter is measured from the hinge, because of the small diameter 1/2" size may vary a 1/16th of an inch. When sizing the materials you wish to insert, please include space for the snap hinged ring to move once it is closed. Here are just a few things that you can do with loose-leaf rings: swatch books, carpet sample books, color reference charts, & display hanging rings.