Derailleur Hanger Extender Bike Gear Hanger Tool Aluminium Alloy Rear Derailleur Hanger Extension for Lower Rear Derailleur Bigger Rear A Must Have for Bigger Cogs on the Back WheelDerailleur hanger extenders attach to the end of a rear derailleur hanger, make the original hanger longer and lower the rear derailleur, allow use of large cogs on the rear cassette. Large rear cogs make it easier to ride up steep hills. How Derailleur Hangers Extender Can Help You?Instead of buying a new compatible rear derailleur with the new cassette, you can use this small extension to get cassette upgrade at a lower cost. Cheaper solution Finely MachinedMade with aluminum alloy material, and are stronger than some steels. Aluminum is also a corrosion resistant metal that naturally generates a protective coating, ensuring a long service life. Specifications Nicely machined and good sturdy mounting extender for the rear derailleur, keep your bike riding great without breaking the bank. Colour: Black Size: 4.5cm*2.3cm Quantity delivered: 2 pieces Warm prompt: 1.As different measuring methods,it will occur 1-3 cm deviation about the items,please ensure that it is okay for you before ordering. 2. Because of different monitors and lamplight, the picture may not reflect the actual color of the item, really thank you for your kind understanding 3. Only the above package contents, excluding other products.