Never out of the storage box shown, this is a set of replacement tubes for the Golden Tube Audio SE-40 Amplifier. The tubes can be used in any other amp with similar tube complement. Consists of two Sovtek 6SN7GTB and six 5881s. The 5881s have been matched and burned-in by Golden Tube Audio (3 tubes per channel). Tubes are marked for their positions in the amplifier. Many other amplifiers use the 5881 and the Sovtek brand is the workhorse used in many of them. New ones usually cost about $20 each. The Sovtek 6SN7GTB is a good replacement for many preamp tubes and usually sells for around $15 each. This set was purchased in 1999. Will ship within US only. No exceptions.