These two NAB aluminum hub adapters serve as accessories for professional recording equipment. Primarily designed for reel-to-reel tape recorders adhering to the NAB standard—such as those from brands like Studer, ReVox, Akai, and Teac—they function as auxiliary tools for mounting 10-inch open-reel tapes. Their precision metalwork and surface finish embody the distinctive industrial design aesthetic characteristic of professional audio equipment.