Hi @danmar123, my point was that the ones you bought from Grant Fidelity has the ringed base, but the one that is pictured on the Grand Fidelity doesn't. The fact the base of the tubes you got from GF look identical to the ones sold by Viva might suggest that they are both manufactured by Linlai but with different letterings. But as I mentioned earlier, Linlai would not acknowledge the ones with the horizontal letterings.
It's good to know that you do hear differences between the ones from Viva and Grand Fidelity. I wonder if the ones sold by Viva and other Chinese retailers are rejects that didn't meet the tight QC requirement, and hence sold at a lower price. Just another guess. The mystery continues...