Ba'ul fighter
Siranna's Ba'ul fighter
The Ba'ul fighter was a type of small, warp-capable attack fighter built by the Ba'ul. It was flown by a single pilot and mounted directed energy weaponry.
After receiving a farewell message from Saru in 2257, his sister Siranna organized a group of Ba'ul fighters to assist USS Discovery and USS Enterprise in their battle against a Section 31 armada. They were contacted by Ash Tyler en route, and thus arrived on the battlefield alongside a Klingon force. (DIS: "Such Sweet Sorrow, Part 2")