Amperex 12BY7A/12BV7/12DQ7  vacuum tube made in Japan 
Tested with a calibrated TV-7D/U tube tester.
Calibration by Daniel Nelson.
Tested at: 58
Average new: 75
Minimum good: 46 
The minimum is equal to 65% of the life of the tube.
Tested for shorts and gas.
Date code: 75-31
Construction: gray plate halo getter copper rods 
Glass: clear
Base: 9 pin
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!