Popular Alternative to EL-34 Tubes.  Subsitute these for EL34 tubes to achieve greater clean headroom and less compression.  Harmonically rich, they sound very full and detailed wiht nice bass clarity.  Some refer to this a a "Super EL34" - this could be attributed to the fact that the KT77 tends to have a higher current draw than normal EL34 tubes.  "KT" stands for kinkless triode as this tube has no kink in the curve of the sine wave.  

You are purchasing a MATCHED QUAD of tubes (x4 tubes total).  Brand New in original packging.