Thanks to the Shimano Shadow RD+ design, the Shimano Deore M5120 derailleur delivers consistent shifting performance for mountain bikes in rough terrain. The flat design prevents damage from impacts with rocks, and Shimano's chain stabilization technology prevents chain drop while providing smoother operation in all gear positions. Mounting type: frame mount. Material type: aluminum. Recommended chain: HG-X 10-speed / 11-speed. Number of gears: 10-speed. Details: Flat design prevents impact damage from rocks. Chain stabilizer prevents chain drop or slap and offers smoother operation.