Abstract: The ring binder mechanism comprises a resilient mechanism cover which can be connected to the spine of a binder or cover, two toggle plates or toggle rods which are articulately connected in opposite senses and which are resiliently supported in the mechanism cover, and ring portions which cooperate in pairs to form rings and which are carried by the toggle plates or toggle rods, consist of drawn or rolled metal wire of non-round cross-section and have ends which positively interengage locally in the closed position. At their free ends, the ring portions have plane end faces which bear snugly against one another in the closed position and one ring portion of each pair of ring portions having a pin which is cylindrical over at least its main length and which projects perpendicularly from the end face and the other ring portion having a bore which is cylindrical over at least its main length and is sunk perpendicularly in the end face.

Abstract: A device for binding holed sheets or a ring book fastener includes a binding cover elastically supported by supporting elements and receiving a plurality of rings spaced from each other along the axis of the binding cover and connected thereto. Each ring is comprised of two ring halves which are releasably engageable with each other. Each ring half is provided at the end thereof cooperating with the end of the other ring half with a tooth-shaped projection engageable in a tooth gap-shaped recess of the other ring half so as to produce a lock preventing a displacement of the ring halves in the closed position in the direction transverse to the closing direction.