Raytheon 6B4G vacuum tube tested strong new old stock
Tested with a calibrated TV-7D/U tube tester.
Calibration by Daniel Nelson.
Tested at: 68
Average new: 63
Minimum good: 38 
The minimum is equal to 65% of the life of the tube.
Tested for shorts and gas.
Date code: F1
Construction: black plate foil getter
Glass: clear
Base is tight
Not tested for sound or noise 
30-day free return.
We combine shipping $1.00 for each extra tube purchase.
Your items will be packed very well and shipped promptly.
Always glad to answer any questions.
Thanks for looking!