For sale is a blackplate Sylvania 5751 tube. It is NOS and it is in an aluminum tube packaged for the Swedish military in the 1950's. It was last tested in 1974 and then sealed up again. This is the one with blackplates and yellow labeling. I am using one in my headphone amp and it is the best tube I have heard and I have tried many. 1950's vintage-the best. $70 + shipping lower 48
