Want all the gain you can get? This is our High Gain Option Retube Kit for the Mesa Rectoverb 25 Heads and Combo Amps. It contains four handpicked High Gain ECC83S's with one being current balanced for the phase inverter in V4 along with two standard ECC83S's for the FX and verb in V5 and V6. The default power tubes are a matched pair of the JJ EL84's but you can configure this kit to use the JJ EL844's for an earlier breakup by clicking on the "Customize" button!