Material and durability: Made from tough plastic for longlasting protection of your For Bike drivetrain. The material resists wear and provides a lightweight guard without adding bulk. Primary function: Prevents the chain from falling behind the flywheel, reducing chain drops and minimizing debris or grease buildup on the frame and hub. This helps maintain smoother, more reliable shifting and pedaling. Compatibility: Designed to work with For Bike disc brake box hubs and derailleur cassettes, making it suitable for bikes that use these components. Size and fit: Outer diameter 138 mm with a 3 mm inner diameter. Please check these dimensions against your For Bicycle model to ensure a correct fit before . Performance benefits: Reduces downtime and maintenance by preventing chain drops that can damage the drivetrain or require roadside repairs. Helps maintain cleaner hub and cassette areas, supporting consistent shifting performance. Lightweight construction preserves overall bike handling and responsiveness. Typical use scenarios: 1. Commuter bikes with For Bike disc brake box hubs where reliable, lowmaintenance operation is needed for daily rides. 2. Bikes with derailleur cassettes used on mixed terrain where the guard helps prevent chain drops during frequent shifting. 3. Any For Bicycle setup with compatible hub/cassette combinations where added drivetrain protection is desired. Sizing check recommended: verify the 138 mm diameter and 3 mm inner diameter fit your For Bicycle model before ordering.