The KMC Bosch Compatible Front Sprocket 11/28 is specifically designed for Bosch E-Bike systems, the KMC Narrow chainring is a perfect solution for replacing or upgrading your current front sprocket. Drive trains on e-bikes with strong mid motors are subject to enormous constant load. Based on that fact, KMC offer specific e-bike chains and sprockets for Bosch motors and internal gear hubs. By incorporating KMC into your drive train you can vastly increase usage and ensure a mileage of over 3,500km. KMC Bosch Compatible Front Sprocket 11/28 Features 1/2 X 11/128 or 1/8 For Bosch II Systems Chromoly Black