Sram GX 11 Speed Rear Derailleur SRAM the Elbow Guard Pro is

the Elbow Guard Pro is perfect for aggressive trail and enduro riding

Frame: 6061-T6 aluminium

it's been widely imitated but never improved upon

rear or both in any condition from winter mud to summer dust

Sram GX 11 Speed Rear Derailleur SRAM the Elbow Guard Pro isThe Sram GX 11 Speed rear derailleur is engineered for smooth, reliable shifting actionfrom the larger upper pulley offset to the 12 tooth X SYNC pulley wheels. By eliminating unwanted chain movement, X HORIZON shifts faster, puts an end to ghost shifting and reduces shift force and chain slap. And with CAGE LOCK technology, wheel removal and installation are easier than ever.