A really nice tube on paper; it's an E180F equivalent and when triode connected comes close the the specs of a 4852. I have two batches of these: one normal and one with thelong-life E variant which also has a taller glass envelope.
As you can see, despite having a large sample size, it is hard to match these tubes into pairs. Just like the 6Z11P, the specs vary enormously, making matched pairs hard to find.
