1x37 galvanized steel strand, 6mm to 12mm, for transmission line messenger and earth wire duty where sag has to stay predictable for decades. A 1x37 strand exists because thirty seven wires give a better balance of strength and surface smoothness than the more common 1x7. There are more wires in contact with clamps and suspension hardware, the outer layer is finer, and the strand runs through a stringing block without the deep surface marks that a coarse seven wire strand