Refrigeration suit

A refrigeration suit suit is a type of clothing worn by the Breen to moderate their temperatures. They also include a helmet with a vocoder. Thots wear a slightly different suit, reflecting their rank. The suits can also be worn by Bajorans, Cardassians and Humans. (, SS DS9 (Requital))

The suits allow the Breen, basically walking sacs of ammonia and gelatin, to hold their body structure in warm climates. Without the suits, the Breen body boils, melts and evaporates. 

In 2375, Weyoun and Corat Damar wondered why the Breen wore the suits, when they learned Breen had a "comfortable" planet. 

Later, Reese and Ekoor used refrigeration suits taken from Cardassia to pose as Breen soldiers in an attempt to assassinate the Female Changeling on Deep Space 9. (SS DS9 (Requital))