This product is a lot of 3 NOS vintage zenith 31LZ6 beam power vacuum tubes, made in the United States. These tubes are unused and in new old stock condition, making them highly sought after by vintage audio enthusiasts and collectors. The zenith brand is well-known for producing high-quality vacuum tubes, and the 31LZ6 model is known for its strong beam power output, making it a valuable addition to any vintage audio setup.