HELP Needed ID stamps in WWI holster

[auswerfer]

I have got a holster, and I belive that it is a wwI holster.

On the back it is marked:

Crown I

and then properly a regiment mark:

8.56

On the front it is marked:

8./J.R.1.56

and on the front by the pull strap it is marked:

721.

Inside the marking for the producer and year is to faint to read.

Notice the later special arrangement for a cleaning rod.

Please advice me concerning the stamps.