Rear derailleur APEX EAGLE.FEATURES:-Eagle range on a drop bar bike´ Now that´s a party.The Apex Eagle rear derailleur quietly and quickly shifts across our 12-speed Eagle cassettes, while 1x-specific chain retention technology keeps the chain where it needs to be.It´s the best of our road and mountain bike innovations in one package.-Compatible with 50T and 52T Eagle cassettes.-Works with 12-speed mechanical Apex and Eagle shifters.-Use with Eagle chain.-Roller Bearing Clutch controls chain tension for consistent shifting.-X-HORIZON straight parallelogram design limits all movement to the horizontal axis, which makes ghost shifting impossible while also reducing shift force.-Cage Lock technology makes for fast wheel changes or chain installation.