These vessels had formidable armaments, with weaponry comparable to that of a Galaxy-class starship. As well, these vessels were nearly as fast and maneuverable. Aside from standard directed energy weapons, they were armed with a form of weapon that caused the crews of enemy ships to suffer from asphyxiation. Federation shields were ineffective against this form of attack.
In late 2366, a Zalkonian warship traversed sector 9569 on an intercept course towards the Federation starship USS Enterprise-D to retrieve the Zalkonian fugitive named "John Doe". (TNG: "Transfigurations")