Bicycle Rear Derailleur Pulley Wheel 12T For-SRAM for XX1 XO1 for X1 for GX NX Apex、 for Rival、 for Force、RED 11Speed. Model: 12T. Narrow wide Wheel. Color: Black(As Pictures Show). The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness.
eBay