According to the Stoeger site their chokes are marked with "notches". Perhaps yours is just a newer or older marking system.
Anyway, one notch is full, 2 is I.M., 3 is modified, 4 is I.C., and 5 is cylinder. They are Winchoke style.
If you go to choketube.com you'll find a very handy choke tube interchange chart that lists most brands/models of shotguns and which chokes fit them.