A ring binder includes a substantially rigid curved upper plate supporting a pair of hinged leaves. A plurality of ring members are secured to the hinged leaves for engaging corresponding holes in sheets of material retained by the ring binder. An actuating lever is located at each end of the curved...http://www.google.com/patents/US6533486?utm_source=gb-gplus-sharePatent US6533486 - Ring binder having actuating lever with cushion member
