Distortion effect for bass with dual gain and dual signal functions. - Model Name: DSGM Bass Distortion - Functions: Dual Gain, Dual Signal, Dual Master - Adjustment Knobs: PRE GAIN, MAS. A, MAS. B, MASTER A, MASTER B - Brand Name: Ongakudo Hirabayashi Thank you for viewing. I assembled it on my effects board once, but I've only used it about twice. Operation has been confirmed. Please note that this item does not have a box. Please refrain from purchasing if you are sensitive to used items.