The UDH Half Mount provides additional protection against incidental knocks and slams by supporting the standard hanger. It provides more protection than a standard hanger, but is not as robust as a Full Mount Eagle Transmission derailleur. Additionally, the UDH Half Mount still requires the use of chain gap and limit screws for proper set up, unlike UDH Full Mount derailleurs. Please note, in order to use the UDH Half Mount, your frame must be UDH compatible.