The Stoeger Condor Over/Under shotgun in 20 gauge uses a Browning Invector choke system, specifically the Invector (not Invector Plus) pattern. This means that choke tubes from other manufacturers compatible with this system will fit, including those from Winchester, Mossberg, and Benelli. Choke tubes from brands like Trulock, Carlson's, and Briley are also compatible. That was from a quick internet search.