Highly compressible open cord

A cord comprising a single layer of helically wound metal filamentary elements,

• each metal filamentary element of the single layer describing, when the cord extends in a substantially rectilinear direction, a helical path about a main axis substantially parallel to the substantially rectilinear direction, such that, in a section plane substantially perpendicular to the main axis, a distance between the center of each metal filamentary element of the single layer and the main axis is equal to half a helix diameter Dh and is substantially constant and identical for all the metal filamentary elements of the single layer,
• the metal filamentary elements defining an internal enclosure of a cord of diameter Dv, and
• each metal filamentary element having a diameter Df and a helix radius of curvature Rf defined by Rf=P/(π×Sin(2α)), where P is a pitch of each metal filamentary element expressed in millimeters and a is a helix angle of each metal filamentary element,
• wherein, with Dh, Dv, Df and Rf being expressed in millimeters 9≤Rf/Df≤30 and 1.30≤Dv/Df≤2.10, where Dv=Dh−Df.