This is a hollow coil which is formed by using more than one rope each made up of multiple strands.
The difference from a single coil is that extension in the longitudinal axis direction is small and the strength against tension is high. This coil was developed to avoid fracture and intravascular persistence of the wire even if the tip of the guidewire is caught in endovascular tissue. Also, the XTRAND coil is characterized by its high flexibility in the transverse axis direction, high torque response, and high torque force.