I bought this and it doesn't fit in the cavity of my bass. I tossed the box already though. What you see is what you get. Here is the description from EMG:
The BQC Control is an active EQ circuit for bass guitars. They allow you separate control over bass, midrange, and treble all via 2 concentric/stacked pots. Rotate the control clockwise to boost, counterclockwise to cut. There is a center detent for flat response. The mid-range control has a variable frequency knob that allows you to sweep through the mid-frequency range from 100Hz to 1KHz. This selects the frequency to boost or cut. The BQC works with active or passive pickups.
The BQC Control is an active EQ circuit for bass guitars. They allow you separate control over bass, midrange, and treble all via 2 concentric/stacked pots. Rotate the control clockwise to boost, counterclockwise to cut. There is a center detent for flat response. The mid-range control has a variable frequency knob that allows you to sweep through the mid-frequency range from 100Hz to 1KHz. This selects the frequency to boost or cut. The BQC works with active or passive pickups.