This part is used on Shimano Shadow rear derailleurs starting 2013.

Will fit a cassette size of 40T or bigger.

Improves shifting performance.

Increases chain wrap, eliminates the need to drastically thread in the b-tension screw.

Replaces the Direct Mount link on 2013 or later Shimano 9, 10, 11-speed Shadow+ rear derailleurs to reduce premature shifting degradation.

Works with any 11-40t or 11-42t 9,10,11-speed cassette.