sylvania jhs12at7 3 mica black plate NOS 1955 prod 4 tubes

these are sylvania's finest 12at7's ever made,a triple mica black plate nos tubes from my extensive collection.having way more then I need or will ever use time to part with some of them.I consider these tubes to be the finest sounding ever produced in the usa and in the top three 12at7 tubes ever made.Excellent depth of field,very natural detail and bass reproduction,imaging is outstanding with a great high end.everything sounds like real music and what more can you ask for,they are my reference 12at7 tubes.they were tested on my hickok 800a recently calibrated tube tester and played through my vtl amps. they are all from same production date in 1955.shipping will be $7.95.thank you.