Specifications: A good replacement for the old or damaged front derailleur adapter. The adapter is easy installation, and suitable for most mountain bike, road bike, and so on. Aluminum alloy material make the conversion shim is lightweight and durable. The conversion shim has great ability to withstand high and low temperatures. 31.8MM diameter frame can be converted into 34.9mm frame, or the 28.6mm diameter frame tube into 31.8mm. So that you can install a diameter of 34.9 / 31.8 mm front dial ring. Item Name: Front Derailleur Adapter Material: Aluminum Alloy Features: Easy to Install, Bicycle Parts, Rust Resistant Size Details 1: 3.4cm x 3.4cm x 1.8cm/1.34" x 1.34" x 0.71" (Approx.) 2: 3.6cm x 3.6cm x 1.8cm/1.42" x 1.42" x 0.71" (Approx.) 3: 3.7cm x 3.7cm x 1.8cm/1.46" x 1.46" x 0.71" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 2 x Front Derailleur Adapters