Very hard to find these. Osram blue labels in very good condition. I just can't use them anymore because I would need four for my new amp. The interior construction is the exact same as in the famous grey glass version. Top tier driver tubes. Tests NOS on my Jackson 648-S tester. No noise, leaks, or microphonics. I'm not the collector type, otherwise I'd put these away. But I'd rather someone get some good use out of them. Priority shipping included.