Abstract: An external fixator system comprises a clamp adapted to couple a fixator pin to a connecting rod. The clamp includes a slot for transversely receiving the body of the connecting rod. The slot preferably includes a region of reduced width, providing interference between the clamp and the connecting rod as it is inserted. This causes the clamp to snap onto the rod. A bolt is inserted through a hole passing through both sides of the slot. The bolt includes a head at one end formed in the shape of a hook adapted to hook the shaft of a fixator pin, and a thread at the opposite end. The bolt is rotatably mountable in the hole such that the fixator pin can be retained at a range of angles relative to the connecting rod. The clamp is attachable to a fixator pin and a connecting bar between two previously-installed clamps without disassembly of the system.