Testing is done with Superior TW-11 Tester. This tester is a cathode emission tester. The results are useful for relative matching of same type tubes, and also a good/bad result. Tubes are checked for filament continuity. The results should be taken as a general indication of tube health.
I am happy to combine shipping on multiple purchases. For USA customers, duty and brokerage is prepaid to ensure quick hassle free delivery.