Both tubes tested Strong NOS (100% - 110%+ mutual conductance) on a Mercury 2000 tube tester with the following result (mutual conductance both in uMhos and in percentage of nominal):
Tube 1: 13,900/13,600(111%/109%)
Tube 2: 14,000/12,500(112%/100%)
Good tubes start at 7000 and new tubes (incl. NOS/NIB) 12,500 - 13,000, and the Mercury 2000's rated mutual conductance (nominal) for new tubes is 12,500. Test result can also be seen in the pictures. In case you wonder what all these numbers mean to your sound experience, it's actually quite straightforward: mutual conductance directly translates to a tube's ability to amplify sound so the higher the numbers the better.
Appearance & cosmetic condition
We treasure this pair also because of the pristine condition of both tubes (clear inscription and clear date codes), which is amazing given the tubes' age. What makes this pair even more rare is the identical date code on both tubes: delta 1L2 (delta = Heerlen, 1 = 1961, L = December, 2 = the 2nd week of the month)