Patent ID: 7670075

Claim:
A binder unit for binding a sheet stack having a mounting hole, comprising: an elongated binding body, which is made of bendable material, having a first binding portion defining a first edge, a second binding portion defining an opposed second edge, and an elongated guiding slot longitudinally extended along said second binding portion, wherein said binding body is adjustably bent in a U-shaped structure with respect to a thickness of said sheet stack, such that said first binding portion of said binding body is arranged for biasing against a top side of said sheet stack at an edge portion thereof while said second binding portion of said binding body is arranged for biasing against a bottom side of said sheet stack at said edge portion thereof to align said guiding slot with said mounting hole; and two spaced apart fastening arms extended from said first edge of said binding body to detachably engage with said second binding portion of said binding body at a position that said fastening arms are slidably coupled within said guiding slot through said mounting hole of said sheet stack, wherein said fastening arms are bent for resting on said bottom side of said sheet stack to reinforce said edge portion of said sheet stack being securely sandwiched between said first and second binding portions of said binding body.