The Holland 12AX7/ECC83 are coded Either I65/Delta5K3 or I65/Delta5K4 It appears the unit these came out of had 2 matched octets of each, all have the yellow/paint dipped tips, some have flaked off a little. I know I only have a few feedbacks here, so I have included a picture at the bottom from a few customers. A few pairs or Quads at the moment. The tubes are ANOS from 1965 and are I65 Internal Construction. They are Philips/Amperex Heerlen, Holland (Bugle Boy Relabels) Philips Plant code, Production Dates I65/Delta563, I65/Delta564 - 1965 - June 3rd & June 4th Tubes all test 81 to 85 where typical new is 90 and replace is 45. As well there are no shorts, gas or leaks. Tested for microphonics and noise also. Prices single, pair/quad are, Price per tube @ $29.99USD. Shipping, insurance and packing materials included. $14.99 USD. They will arrive packaged very well. Total price per single $44.99 Pairs $74.99 or Quad - $134.99 USD, shipped, insured and packaged bulletproof. 100% money back guarantee, if you are unhappy for any reason return for full refund no questons asked. I am happy to provide references for anyone. SOLD - Quad of 7189(Industrial El84/6BQ5), Philips/Amperex Canada. Tests Results - Pretty close to matched @ 83,83,82,84. 90 is typical new power tube test results on my tester, 45 is replace/ bad.