A. This bicycle derailleur hanger converter is made of aluminum alloy, offering good durability and stability, and can provide reliable support for your cycling experience. B. It comes in two specifications: the long version L41 and the short version L23. Different specifications can meet various usage needs. Whether it's a road bike or a mountain bike, you can find a suitable converter. The long version L41 can achieve a longer derailleur hanger extension, providing more expansion space for the bicycle, which is suitable for cycling enthusiasts with higher requirements for frame space. The short version L23 is more compact and can meet the needs of those who don't have high space requirements but need precise adaptation. C. This derailleur hanger converter can be used as an extension seat for mountain bikes and can also be adapted to rear derailleurs and cassettes, effectively improving the performance of the bicycle. It can make the operation of the rear derailleur smoother and the shifting more accurate, allowing you to easily handle various road conditions while cycling. D. Whether you're speeding on flat roads or shuttling through rugged mountains, this bicycle derailleur hanger converter will be a good cycling companion, adding more functions and practicality to your bicycle.