any one know about Amperex el34 fatboy tubes

any info on theses tubes; good bad how much they can cost..thanks
They are frequently for sale at EBAY. I like them but ultimately prefer the Mullard EL 34, XF2 (with British mfg. code).
Hello, Albert, what is the cost of the Mullards and where can they be purchased?? Thanks
I have 4 Mullard EL34 XF2s for sale (used but test well). 1960s manufacture. Email me if interested