Like many manufacturers, Carrier converted their production to military use during World War II. Carrier systems were used in the production of synthetic rubber and in high octane gasoline both of which were vital to the war effort. Carrier chillers were removed from department stores including Macy's department store for installation in military production plants and were returned after the war. Carrier air conditioning and refrigeration equipment was used for warships, cargo vessels, munitions plants, and factories specializing in the production of such essential war material as bombsights and other precision instruments. Carrier made thousands of refrigeration units for walk-in coolers which were used by the Navy to keep food and other perishables fresh. Special portable air conditioners were made for servicing airplanes in hot climates. Carrier also turned out airplane engine mounts, sight hoods for guns, tank adapters and other military items.