Through its exclusive lightweight structure, Shimano's patented Spiral X construction enhances catching power for anglers. Spiral X construction consists of three layers: a middle layer of vertical fibers as well as inner and outer layers, both comprised of carbon tape that tightly winds the blank diagonally in opposite directions. By using this carbon tape in place of a conventional horizontal fiber sheet, Spiral X achieves enhanced compression rigidity and increased torsional rigidity without adding extra weight. This in turn facilitates instant power transmission for precise casting and fish fighting.

CI4 is a Shimano original material reinforced with carbon fiber that is lighter and has a higher strength than conventional resin material. CI4+ is an advanced version of the original CI4 material and is 2.5x more rigid than its predecessor. While improving lightness and rigidity, reel bodies, rotors and reel seats built with CI4+ are further reduced in size and weight.