The Sovtek 5881WXT power tube is the same as the 5881 but with a full-size base for easy installation in vintage amp designs. Used by Fender, Crate, Carvin, and amplifier manufacturers.
These Sovtek 5881WXT tubes are in platinum matched sets. Sovtek's platinum matching process consists of a 24-hour tube burn-in period followed by a bias (plate) current measurement in milliamps.
Order tubes BEFORE they need to be replaced, and save the gig.