Beam tetrode power tube. Brand new vacuum tubes made OEM for Mesa Boogie by Shuguang. They were to be used in new amp production and are not labeled or packaged to be on a sales shelf. Other tube/valve numbers 6L6GC, 6L6G, 6L6GA, 6L6GB. These tubes are compatible with 5881 and any 6L6 .
Tested on the RoeTest professional computer testing system.
Matched sets are matched by plate current and transconductance using the new Maxi Matcher 2