Bicycle Rear Derailleur Hanger 40T 42T 44T 46T 50T 52T 56T Bicycle Tail Hook Extension Extender Bike Frame Gear Tail Hook Extender Enlarging Flywheel Speed: Bicycle rear derailleur hanger amplifies the speed of the cassette for smoother shifts, a great accessory for cyclists. Improve Climbing Ability: Bike tail hook extension extender can relieve the spring tension of the rear derailleur and improve the climbing ability of the bike. Aluminum Alloy Material: Bike rear derailleur hanger is made of aluminum alloy material, CNC precise machining, durable and easy to install. Scope of Application: It can be increased by 41mm, and the tooth volume of 20 to 22 teeth can be increased. It is often used when the large teeth of the rear flywheel are changed to 40T 42T 44T 46T 50T 52T. Good Workmanship: Professional manufacture, exquisite workmanship, beautiful appearance, stable performance, high reliability and long service life. Color: Black Size: 63*23mm Delivery Quantity: 1 Piece