Material Teenso Front Derailleur Conversion Shim is a bike front derailleur ring, made of premium plastic material, sturdy and durable Wide Application 31.8mm Front Derailleur Clamp Shim is suitable for mountain bike, road bike, and other types of bikes High Strength Lightweight, high strength, durable for long time use. 31.8MM diameter frame can be converted into 34.9MM frame Good Performance You can replace the old one, and provide the good performance for your bike Specification Material Plastic Color as picture shown Diameter 3.7cm/1.5inch Package List 2 x Front Derailleur Conversion Shim.