Rohloff Upper Chain Guides.Mounts in place of a front derailleur to the seat tubeIncluded spacers allow for precise chainline alignmentFits 28.6mm, 32.0mm, and 35.0mm seat tubes (shims for 28.6mm and 32.0mm included)Item SpecificationsFront Derailleur Clamp31.8mm (1-1/4"),35.0mm (1-3/8"),28.6mm (1-1/8")