What Our Gearhead® Experts Are Saying:"I like the Box Three Prime 9 X-Wide because it gives riders a super clean, no-frills drivetrain that just works. The limited slip clutch keeps things quiet, the sealed pulleys last way longer than you'd expect at this price, and setup stays painless thanks to the wide-range 11–46 or 11–50T compatibility. It’s a great upgrade if you want durability without overthinking your drivetrain."The Box Three Prime 9 X-Wide Rear Derailleur brings the simplicity of a nine-speed system to modern wide-range riding. With fewer gears to manage and a straighter chain line, the Prime 9 layout delivers smooth, intuitive shifting on everything from gravel loops to singletrack climbs. A limited slip clutch keeps the chain quiet and controlled, helping every ride feel more focused and confidence-inspiring. Designed with sealed bearing pulleys and a solid, serviceable construction, the derailleur is built to handle seasons of hard miles. Its broad compatibility with 11–46T and 11–50T cassettes turns it into a versatile option for riders who want modern range without the maintenance demands of higher-speed drivetrains. Simple, tough, and impressively capable, it’s a drivetrain solution that puts reliability first.