The Cartridge Rod Holding Tool allows you to more easily disassemble and assemble KYB and Showa Twin Chamber and most street cartridge forks. When applied, the tool holds back the spring force allowing you to loosen or tighten the bottom nut or the fork cap on the cartridge rod.
Everyone complaining about this tool being a cheap piece of plastic and metal being better, your twin chamber cartridge rod is aluminum with hard anodizing. The second the rod spins inside of your metal shaft holding tool you will gouge the rod which will likely tear your cartridge seal. Plastic will not compromise the hard anodizing on your cartridge rod.
This tool will gouge your cartridge rod if you get it installed slightly crooked or if you get the tool slid on too far up the rod and allow the rod to retract while inside the tool. Its thin steel, and not friendly to the rod like the thick alum versions.