The picture shows a well decorated veteran Unteroffizier , EKII, Ost front, Infantry assault, black wound badge. He appears to be wearing his walking out uniform ( silver buttons ) . The slip on 10 on his shoulder boards is rather old fashioned and would not have been worn on,or close to the front line.
88th Div. 246th regiment fits this profile, as it spent most of its time on the Eastern Front; it could be that this gentleman was transferred, for a period of time , to a different unit , for any number of reasons. Sorry I can't pin down the number 10 more specifically.