Mazda (Toshiba) High Reliability Tube 5651 Toshiba 6AQ5 6X4 5751 (High Reliability Tube) 6AK5 x 3 tubes Matsushita Electric (National) 6AQ5 Amperex 6939 The box is Motorola, not Amperex. Hewlett Packard 6843 HP is a high-end measuring instrument manufacturer, and I believe this tube was used for measuring instruments. TEN (Kobe Kogyo → Fujitsu Ten) 6CB6, 6763 (High Reliability Tube) That's all, 12 tubes in total. Thank you. These vacuum tubes are unused, but there may be some deterioration due to age. They were mainly stored as maintenance supplies. They are of high reliability, communication, and measurement quality. Thank you for looking.