The shotgun comes with a 'cylinder bore' choke, and it is 'fixed'. This gun does not use choke tubes. You might get it threaded to use tubes after purchase by a good gunsmith or machinist. However as a 'defense' shotgun, it is a 'fixed' choke.

Curtis, this shotgun has a Fixed Cylinder Bore Choke.. ------ ((Specifications and features)): - Interstate Arms model 981 Defender pump-action shotgun - 12 gauge - 18.5" barrel - 3" chamber - 5 +1 capacity - Cylinder bore choke - Synthetic stock - Matte black finish.
Bead sights
38-1/2" overall length
7 lbs.