Hot Fire Birds was made by German manufacturer NSM. It runs on their own operating system. The cabinet is generic, and made out of metal with a woodgrain pattern covering. The playfield and all parts on the playfield were made and probably designed inhouse at Gottlieb, essentially making this a very rarely seen Gottlieb design.
Hot Fire Birds and Cosmic Flash are the only 2 machines made by NSM that have an all original playfield layout, artwork and software. All other machines by this manufacturer were copies of existing Gottlieb games, except for the cabinet and operating system.