This Medi was produced in East Germany and is very robust.  The MEDI name comes from VEB Medizintechnik Leipzig, however I believe this model is called the Hydromat 62004.  This is the early model and was made about 1962 or `963.  The Medi was originally made for the DDR Volksmarine  (East German Navy), but was later made a sold to civilian divers.  The Medi came with double or triple 7 litre tanks.  It is DIN only and a good breather.  These are very common even in the USA and parts are still available.  This particular Medi came to me with a wrench for on the spot field repairs.