AROMA AMX-3 MATCHBOX D.I. Transfer Guitar or Bass Signal Directly to Audio System Mini Analogue Effect Pedal True Bypass Effect: CAB SIM,Full metal shell Cabinet simulator switch: Switch the 4 * 12" cabinet simulator on and off. Gain: Switch the gain between -20dB, 0dB and +20dB. GND switch: It can eliminate hum or ground loops depending on the grounding of the connected equipment. Input jack: 1/4" mono audio jack for connecting guitar.