Want the smoothest richest tone possible from your Mesa 22, Studio 22 or Studio 22 Plus, but you also want the earlier breakup of the EL844's? This kit contains a matched pair of JJ EL844's to drop the overall output a couple decibels for the power section. Four standard Gold Pin ECC83S's for V1 thru V4 and a balanced Gold Pin ECC83S for the phase inverter in V5.