Sylvania 6AH4GT vacuum tube new old stock in box 
Tested with a calibrated TV-7D/U tube tester.
Calibration by Daniel Nelson.
Tested at: 101 
Average new: 95
Minimum good: 57 
The minimum is equal to 65% of the life of the tube.
Tested for shorts and gas.
Date code: BL
Construction: black plate [ ] side getter
Glass: clear top 
Base: tight
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!