I bought several matched pairs of these as NOS in 2015 but I struggled to get four reliable pairs, which I needed for my Audio Innovations 2nd Audio power amps. I became disillusioned with the number of them I had to return due to heater problems and actually never managed to obtain a full set of eight of these valves. I then switched to 6C4C types, which although lower power, were always reliable.

I was left with three good NOS Sovtek 6B4Gs which all worked properly and have remained in the drawer ever since.  I am now having a long overdue clear out so hopefully these will be of use to someone - they are becoming quite hard to find!

This listing is for a pair of valves, their numbers on the boxes don't mean anything to me but they may help you to decide if they will suit you.  They are listed as used, but really it's as close to NOS as you can get.  The other good one is listed separately.