Cardinal 11832 SuperStrength Locking Slant-D Ring Binder, 4" Cap, 11 x 8 1/2, Black Extra-firm locking mechanism to prevent spills and eliminate all gaps Easy-to-grasp oversize trigger Slant-D rings hold 25% more than standard round rings Patented Expand-A-Pocket in back holds an additional 1/2-inch stack of paper DataGuard inside pocket protects documents from ring impressions