Shimano xtr m986 shadow 10 speed rear mechxtr shadow plus dyna sys 10 speed rear derailleur for the ultimate in shifting performance and durability shimanos new direct mount rear derailleur system gives more space around the rear frame dropout resulting in easier rear wheel removal but also allows frame designers to shorten chainstays increase axel sizes and move suspension pivots featuresdirect mount gives a simpler cleaner lookshadow plus features a super low profile designshadow plus use