ZVEX Effects Vextron Distortron Guitar Effects Pedal Works well in combination with other distortion pedals DC power jack on side of unit uses standard Boss configuration (with center negative) LED light indicates when unit is operational and when battery is low Gain switch: "Lo/Hi" switch lets you choose the standard "Box of Rock" gain level or a slightly boosted level Subs switch: '2-1-3' switch lets you choose the standard "Box of Rock" sub amount (on option 3) or two different lower levels of subs, depending on your amp's needs