A bolt is adapted to clamp a pin to an external fixator system. The bolt includes a shaft having a threaded section, a head section and a pin opening that is arranged opposite the threaded section and accommodates and clamps a pin or a wire to a plate or ring of an external fixator. The plate comprises at least one opening which accommodates the shaft and a surface against which the pin or the wire is clamped by the bolt. The pin opening comprises at least two edges extending essentially along the same direction as the pin opening such that the pin or wire to be clamped is contact with said edges.
