Breather
A breather was a type of breathing apparatus that allowed Barzans to breathe their own form of air while in an alien atmosphere. These devices were worn whenever they left their homeworld Barzan II. The device provided them with the gasses that were found in the atmosphere of their homeworld that were toxic to other species. (; ) 

After being relocated to the 32nd century from the 23rd century, then departing  in 3189, D. Nhan noted, upon her return to the ship in 3190, that she had gotten an upgrade of her breathers since the Discovery crew had last saw her. ()

Life support technology