DJC Road Bike Front Derailleur 12S ExtenderFeatures:Fit : for Shimano 12s Di2 Dura-Ace R9250 R9200/ Ultegra R8150, R8170, R8100/ 105 R7150, R7100/ FORCE AXSSupport: only fit 10s, 11s, 12s road bike, NOT fit mountain bikeFunction: if want to use super big/small tooth like 46T or 54T 55T chainring, you need to make the front derailleur higher or lower, this extender can help to reach this targetRise/lower distance: 15.5mmMaterial: 304Weight: about 9gPackage contents: 1 x 12s extenderNotice: This extender only for road bike use, not for mountain bike!!About:Stone Design Workshop focus to offer high quality and innovated design CNC processed chainrings to clients in worldwide, especially favored by EU race teams. Provides customize rings on tooth quantity and style as well as add team logos or name base on Stone logo.Material is basic of everything, Aluminum 7075-T651 supplied by Aleris and Alcoa USA, which is top aluminum supplier in world wide, Aleris is supplier to many aircraft make.