From Weatherbys web site...
Beretta/Benelli Mobil Choke
Models that use this choke pattern:
PA-459 (all)
SA-459 (except Turkey Xtra Green)
SA-459 Turkey Mothwing Spring Mimicry (Discontinued Model)
SA-08 (28 Gauge only)
Element (28 gauge only)
Suggested aftermarket choke tube manufacturers: Trulock, Carlson's, Briley Manufacturing.