Old stock. The tubes are new and never used
"FOTON" factory
Different Date from 1950's
Tested and Measured Pair 6P3S (6П3С) Tetrode
We test our tubes from this type on High-End Tube Tester: L3-3
Measured parameters attached to each tube, difference < 3%
on the photo shows an example of the tubes with parameters
Lot of 2 (Matched & Balanced Pair)