For your consideration - a beautiful matched quad of Ei KT90 Type II! This version of the KT90 (easily identified by the numerous spot welds on the plate structure) is widely regarded as best sounding and most reliable KT90 ever made. For amps that call for 6550 / KT88 / KT120, these tubes are the gold standard. These examples came in a bulk case of VTL-branded tubes, so original boxes are not available. These tubes were digitally tested with a MaxiMatcher II. As you can see in the picture, the tubes are incredibly well matched for Gm! On the MaxiMatcher II, Gm > 3.1 is considered good for KT90. Tubes pictures are the actual tubes for sale. Please contact me with any questions!