The guitar has a mini-toggle switch just below the bridge that activates the pre-amp that is installed in the rear cavity of the Tele. It uses a 9v battery and adds a nice instant db boost when activated. The third knob on the guitar is gain, and it has A LOT of gain to this pre-amp. Several people think that it’s the same pre-amp as the Eric Clapton Stratocaster, or the EMG active system, but I have learned it is based on neither. About the closest thing I can equate it to is a MXR Micro-Amp preamp. It does definitely change the tone when activated, but can come in handy for solos for sure. The gain knob is gets almost into “fuzz” gain when dimed out….so it probably wont get much use on “10”.