<p>Loose leaf binder ring is a very common used office supply, made with multi-layer nickel-plated metal that will not crack or split. Rings open and close easily and lock for extra security. </p> <br/><p>The set includes 4 sizes (0.6 Inch/1 Inch/2 Inch/3 Inch )different book rings. </p> <p>0.6 inch/15mm (ID) book rings, 20PCS</p> <p>1 inch/25mm (ID) book rings, 12PCS </p> <p>2 inch/50mm (ID) book rings, 6PCS</p> <p>3 inch/75mm (ID) book rings, 2PCS</p> <p>If you can not decide what sizes book rings you want or need different sizes book rings, this assorted book rings set is a very good choice for you. </p>