RCA 21LU8 Vacuum Tube Valve NOS NIB Matched Pair 6AU6 These four RCA and Cunningham

These four RCA and Cunningham number / type 27 tubes tested as low goodand good on our Paul Hart-calibrated TV7/U

It also sounded great in my Schiit Audio Vali 2 headphone amplifier

The spine is in fine shape with no loose pages and APPEARS to be leather-bound

new in box Sylvania 10GK6 tubes tested to spec on our Paul Hart-calibrated TV7/U

They measured 62 and 76 where minimum (65%) is 46 and 100% is 71

RCA 21LU8 Vacuum Tube Valve NOS NIB Matched Pair 6AU6 These four RCA and CunninghamThis new old stock, new in box RCA 21LU8 tube tested to spec on our Paul Hart calibrated TV7 U. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT LISTED, WE MAY HAVE IT. PLEASE ALSO SEE OUT ETSY SISTER SITE "LOWTECHTWOO" AND OR CALL OR TEXT US AT 202 372 6931 IF YOU DO NOT SEE WHAT YOU NEED OR HAVE ANY QUESTIONS. 1. MOST OF THE TUBES WE SELL ARE OVER 70 YEARS OLD. WE CANNOT GUARANTEE FOR FAILURES AFTER POWER UP AS THERE IS NO WAY TO DETERMINE