These are Electro-Harmonix EL84EH power tubes in platinum matched sets. The EL84 is the most common
low power pentode tube, popularized in early Vox AC30 amps. Rediscovered by Matchless amps and now currently used by nearly
every tube amp company. Delivers quick, soft overdrive distortion, great for recording but usually too low volume for live
gigs.
Electro-Harmonix' 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.