Solid State Logic 611 EQ, 500 Series - 1 channel EQ, SSL 4000 E Series circuitry, "Black-242" and "Brown-02" twin EQ design, Versatile 4 band channel EQ, Bell curve option on HF and LF, Fully parametric LMF and HMF with Q, Based on classic 611E console channel strip, Format: API Series 500, Mounts in 1 space in a "500" rack