Reference binder offers a Slant-D locking ring mechanism for added security to protect your letter-size documents. Extra-firm locking mechanism prevents spills, eliminates all gaps and is easy to grasp with the oversized trigger. SuperStrength Slant-D rings hold 50 percent more than standard round rings. Back-mounted steel rings reduce wear and let pages lie flat. 3" ring capacity holds approximately 725 sheets. Patented Expand-A-Pocket expands to hold up to 1/2" of material. Interior DataGuard pocket protects your documents from ring impressions. Binder also features exposed rivets and a sturdy chipboard core.