Want all thew gain you can get? This is our High Gain Option Retube Kit for the Gibson GA 20RVT Combo Amps. It contains two standard ECC83S's for verb V3 and V4 along with three handpicked High Gain ECC83S's with one being current balanced for the phase inverter in V5. The power tubes are a matched pair of the JJ 6V6S's.