Regimental shoulder strap

[KyleSchuette]

I don’t know much about these. Does this look authentic to you or how can you tell? What era might this be from? Thanks in advance.

[aicusv]

This is a strap from the Dunkelblau (dark blue) uniform (pre-war), for Infanterie-Regt. Graf Bülow von Dennewitz (6.Westfälisches) Nr.55 (Detmold; I Bn Höxter; II.Bn Bielefeld) VII Armee Korps.