The SRAM XO Type 2 10-Speed Long Cage rear derailleur was designed to keep your chain tight and your drivetrain running smoothly. With Roller Bearing Clutch technology, SRAM Type 2 eliminates derailleur bounce and chain slap without sacrificing precision. Because of the super-tight spring, this Type 2 derailleur features Cage Lock technology.
Strengths: Shift precision
Cage lock is a nice feature for servicing
Weaknesses: A tad bit heavier than the normal XO by approximately 30 grams. But that's only a worry for true weight weenies.
I got this as a take-off part from eBay. I can't believe that someone did not want this part. Quiet, no chainslap, precise shifts. The cage lock feature helps a ton when installing a new chain or servicing. The best der I have ever owned.