Compatibility: Designed for use on mountain bikes, road bikes and multi-speed (variable speed) bicycles. Fits applications where a durable guide/jockey wheel and screw assembly is required. Function and performance: The concave guide wheel screw secures the pulley and maintains correct alignment, while the quiet (silent) guide wheel delivers smooth, low-noise shifting. Together they improve shifting accuracy and reduce drivetrain noise. Durable construction: High-strength construction and a wide connection design provide a more stable mounting interface, resisting wear and maintaining precise shifting over time. Easy maintenance: Simple, service-friendly design makes installation and removal straightforward, so you can replace or service the part without complicated disassembly. Key benefits for riders: Smoother, quieter gear changes for more confident riding Improved shifting precision and longer component life due to robust connection design Fast, low-effort replacement or maintenance to get back on the road or trail quickly Use scenarios: Replace worn jockey wheels on a mountain bike to restore crisp, quiet shifting during long trail rides. Upgrade a road bike’s derailleur pulley assembly to reduce drivetrain noise and maintain precise shifting at higher cadences. Carry as a spare or use in routine maintenance for a commuter’s multi-speed bicycle to ensure reliable, durable performance. What’s included and what it does: Concave guide wheel screw combined with a silent guide wheel, engineered to provide smooth, easy shifting, reliable fastening, and extended durability without adding complexity to installation or maintenance.