BOSS CS-1 Compressor Sustainer with Normal and Treble controls. - Model Name: CS-1 - Brand: BOSS - Function: Compressor Sustainer - Controls: Normal, Treble - Power: DC-9V *The contact for the red check lamp sometimes becomes poor and does not light up. Power has been confirmed and the unit has been tested, but please understand that this is a used item. Thank you for looking.