This part is used on Shimano Shadow rear derailleurs starting 2013
Will fit a cassette size of 40T or bigger
Bolt included
Improves shifting performance on 1-10 systems
Increases chain wrap, eliminates the need to drastically thread in the b-tension screw
Replaces the Direct Mount link on 2013 or later Shimano 10-speed Shadow+ rear derailleurs to reduce premature shifting degradation
Works with any 11-40t or 11-42t 10-speed cassette