SER (AB Svenska Elektron Rör) Sweden are best sound for the money hands down. Even though these are some of the hardest to find 6X4 variants ever made, we were able to get a limited supply in original boxes, each tube wrapped inside the box.
Founded in 1938, SER was later purchased by Ericsson and they often subcontracted for GEC, Western Electric and others . SER made some of the highest quality NOS European tubes ever. These are very rare D Shaped Foil Getter with black plates. Just $29.99 per tube! Get them while supplies last.