Shimano ZEE RD-M640 Shadow Plus Rear Derailleur

By increasing spring tension when it's engaged, the clutch reduces slap and the risk of dropping a chain, making it a killer choice for riders who spend decent chunks of their time pounding through rock gardens and over rugged trails. When the clutch is off, the reduced tension makes it easy to pop the derailleur out of the way for wheel removal. It's made of aluminum and steel, so it's durable enough to be knocked around with no ill effects, and comes in both a DH and Freeride model, so you can dial it in for the type of riding you do most often.
-Rear derailleur for 10-speed gravity mountain bikes
-Short-cage accommodates up to a 36-tooth cog in free-ride
-Quieter drive train and chain stability with Shadow RD+
-Low profile design tucks up to avoid close calls on trail
-Compatible with 10-speed Shimano mountain shifters
-Item #SHI002H