4 x 12ax7 RCA Tubes

Made in USA

Long Ribbed  Black plates

 D or slant getter

Red Tipped = Medical Grade

Pictures show actual

Matching codes 58-17 = 1958
 
Tested on calibrated Hickok 6000A

1110/1100 micromhos
1120/1250 micromhos
1280/1120 micromhos
1210/1230 micromhos

Mutual conductance (100%) = 1250/1250 micromhos

I do combine S&H when possible