CN-M9100 Smoother driving even over bumpy terrain Greater chain retention to extend portion on the end of inner plate to firmly hold the tooth both front and cassette sprocket Enhancements to shifting performance Compatible with new generation of drivetrain QUICK-LINK (SM-CN910-12) Easy connect Quick assembly tool also available Non-reusable QUICK-LINK connecting removing pliers (TL-CN10) SL-M9100-R Quicker lever access and light operation force maintains rider concentration 20% quicker lever access time -35% shifting operation force (vs. M9000) Greater flexibility and action-optimized cockpit layout CS-M9101-12 Definitive shifting Let you pedal continuously while shifting Increased acceleration by reducing inertia and weight by BEAM SPIDER construction New MICRO SPLINE * construction to engage FREEHUB body RD-M9100-SGS Enhance shifting performance Optimized for new drive system Silent drivetrain Decreased rear derailleur tension at low gear position, to prevent high chain tension at low gear Add bumper at rear derailleur pulley cage Bigger 13T pulley Low profile design SHIMANO SHADOW RD+ Low sprocket combination 10-51T (12-speed) ***These are OEM Shimano Parts, Brand new, Never Installed on Bike, Never used in any way, just NOT in the retail packaging.***