I am standing on the hose...you want to know what tunics had been used before 1919?
Difficult, because Reichswehr used and altered nearly all of WW1 tunics in the first jears after the war due to the regulations of 1919 (this is why this tunic-type is called M1919): new collar and cambered...
it is a M1919 tunic used in WW1 (stamp of saxonian IR 139) and altered for provisional Reichswehr- but the collar cloth had been removed and also the cuffs...