Shimano Dura Ace R9100 and Ultegra R8000 Oversized Derailleur Cage - Fire-Engine Red
Kolossos is the Greek word for a statue, much larger than the original subject. Seems fitting for an oversized derailleur cage with a 19 tooth bottom wheel.
Besides reduced friction, this cage is built with shifting accuracy, gravel worthiness and chain retention in mind.
This model will fit on Dura Ace R9100 and Ultegra R8000 series derailleurs. This includes mechanical and Di2 as well as short (SS) and medium (GS) cage lengths.