Designed to offer better system performance this optional S100 Half Mount derailleur outer plate features UDH bolt integration to provide extra robustness in the case of side impacts knocks and slams. For use with S100 Eagle derailleurs only on frames that feature the Hangerless Interface required for UDH (UDH sold separately)Adds valuable security to MTBs and eMTBs where the added weight of the system can cause extra damage in a simple fallHalf Mount plate integrates with the UDH bolt and the Half Mount specific S100 Eagle rear derailleur mount bolt (UDH sold separately)