V3 1x guide. Alloy ISCG 05 New Co-mold rubber upper guide for truly silent running 26-38T Compatibility Black New wide chain line adjustment guide (CHMRUV3OK) is for new bikes with 148mm boost rear end but 3mm wider ISCG 05 tabs. This will cause chain guide alignment issues with some bikes and guide set ups. So this guide sets the upper guide back at a position that will align with correct chainline.
"You may just be the type of rider that should be using some sort of chain guide. Some people, especially those who are pushing hard and going fast over rough terrain, are just always going to need some sort of chain guide." - Mike Levy, Pinkbike 2015.