Shimano RD-M739 rear derailleur offers precise and smooth gear shifting for mountain bikes. With a total capacity of 39T, it can handle a wide range of gear combinations, making it suitable for various riding styles and terrains. The SIS (Shimano Index System) ensures accurate and consistent shifting, while the low-friction design minimizes shifting effort. The RD-M739 is compatible with Shimano's Rapidfire SL shifters and IG chains, providing a reliable and efficient drivetrain system for your mountain biking adventures.