Shimano RD-C030 is a rear derailleur designed for 7-speed SIS systems, offering precise and smooth gear shifting. It features a Smart Cage design for improved chain stability and shifting performance, and is compatible with a wide range of sprockets, including 11-34T. The RD-C030 also comes with a reinforced connecting pin for secure chain connection, a low-friction pulley system for efficient shifting, and adjustable B-tension for fine-tuning derailleur performance.