Superior power Beam tetrode with large plate dimensions and improved grid structure for increased power handling capabilities. Pricing is per tube. • Modeled after the vintage RCA 6L6GC "blackplate" • Mica spacers with metal springs eliminate tube rattle and microphonics • 5881/KT66 equivalent Electro-Harmonix tubes are all new designs and are of excellent quality. Many OEMs use relabeled Electro-Harmonix vacuum tubes in their amplifiers. If you want great sounding tubes at a very reasonable price, then Electro-Harmonix tubes should be on your list.