Thank you for viewing. This is a Toshiba 5V 4G rectifier tube. - Brand: Toshiba - Model: 5V 4G - Type: Vacuum tube - Condition: Unused I purchased this as NOS (New Old Stock). The characteristics were written on the box at the time of purchase, so I believe testing was performed. I purchased this from a specialist online retailer, but I have no plans to use it, so I am offering it for sale. I do not have the equipment to test it, so I cannot confirm its operation. If it is unusable, I will provide a refund. Thank you for your understanding.