Tret's containment vessel
Tret's containment vessel was a class of starship utilized by Tret's species to prevent any individual infected from the Loque'eque mutagenic virus from leaving the Loque'eque homeworld and infecting neighboring star systems. This class of vessel was armed with dual forward particle cannons, and were capable of exceeding warp 4. During the 2150s, a vessel of this class was commanded by Tret.

In 2153, Tret's containment vessel, and one of her sister ships, intercepted  in orbit of the Loque'eque homewhere, where they discovered a Loque'eque aboard the Human vessel. They declared that Enterprise was under quarantine, and that it they should prepare to be boarded. The commander of Enterprise at the time,  refused to be boarded, but offered to Tret that he may come aboard to discuss the situation. After departing Enterprise, Tret returned to his vessel, which remained in orbit alongside her sister ship and the Earth ship. 

After Enterprise attempted to flee the two containment vessels, they both took chase, and quickly caught Enterprise, after nearly disabling her aft hull plating. Threatening to destroy Enterprise, the two ships stood down after they were offered an antitoxin capable of reversing the mutagen. ()

Background information 
In the final draft script of "Extinction", the only physical description of the containment vessels were that they be "sizable".

The containment vessel only made one appearance and was designed by John Eaves. Eaves was less than enamored with the design, however, or as he has put it, "UHHHHGGGGG!!! as in ugly, by far my least favorite of anything I have ever drawn. based on a hatchet in a tool pouch it goes to show that not all shapes can inspire a spacecraft idea. HAAAA this one is embarrassing!!!"  Nevertheless, the design was approved in  and was sent over to Eden FX, where the design was turned into a CGI model by Pierre Drolet, whose modelling did not soften Eaves' opinion. "Even Pierre's brilliant modeling," Eaves remarked, "couldn't stop the fairies with ugly sticks from beating the tar out of this one!" 

Unnamed starships
Starship classes