The LM-AD-1-1T is a special adapter using the threaded socket in the display head to solve the mounting problem that many of the newer display heads create, in particular the FTM-400, FTM-350 or FTM-100.
The LM-AD-1-1T will work with all Lido Mounts that have a single T like the LM-801 or older versions of our LM-500 or LM-300