Shimano XTR Rear Derailleur M980 10spd Top Normal
10psd Shimano XTR rear mech - shadow. Medium and long cage can be used on double and triple mtb cranksets.
Note - not compatible with 9spd shifters!
Shimano say :-
The new 10-speed XTR rear derailleur sees a re-engineered architecture that provides a smooth, linear feel at the shifter and is remarkably stable despite suspension movement, trail chatter or inevitable cable contamination.