The Crusader-class Gunship or just Crusader Gunship was the Zann Consortium's only Corvette class starship. It was most effective at Anti-Fighter duty. They are created by Mandal Hypernautics. They were primarily used as anti-fighter patrol vehicles but they could also fulfill a variety of other roles including support vessels for larger capital ships. If used in groups they could also mount their own attacks on lightly defended enemy positions.
The Crusader has a wide variety of strengths which include it being able to effectively fend off and destroy any fighter or bomber it comes across as well as having a point-defense cannon which can shoot down and disable any missile or torpedo that it comes across. But the versatility isn't all, they are very fast, they build quickly, and come at a fairly cheap price.
While the Crusader is indeed effective against small-size starships, it was vulnerable to frigate and capital ships. It's effectiveness against frigate, capital ships, and even other corvettes is very low and aren't known for their durability.