Dual-Pull Cable Routing ( Convenient Dual-Pull feature allows derailleur to be set up for top or bottom cable routing according to cable anchor position). Compatible With Three Frame Tube Sizes (Ring spacers allow the derailleur to be mounted to 28.6mm & 31.8mm frame tubes. Reinforced Chain Guide (Special chain guide cross section offers high strength and rigidity for improved shifting response). Mega-9 Compatibility (Designed specifically for use with super-narrow 9-speed chains). Top-low Max. Capacity: 22T. Top-middle Min. Capacity: 12T. Top Gear Teeth: 44T. Mount Type Band Material: aluminum anodized. Outer Link: aluminium/anodized. Inner Link: aluminum/painted. Chain Cage: steel/nicked plated.