Here's what Ampeg say about the Classic Bass Preamp:

The Ampeg Classic Analog Bass Preamp pedal is like having a choice of Ampeg amps right on your pedal board. Dial in a wide range of authentic Ampeg tones with the 3-band tone stack and highly flexible Ultra-Hi and Ultra-Lo circuits. It’s the most affordable way into the pure analog bass tone of Ampeg.

Features:
- Delivers a wide range of authentic Ampeg tones
- Classic 3-band tone stack plus volume
- Ultra-Hi and Ultra-Lo circuits for tonal flexibility
- True bypass, analog design with incredible signal-to-noise ratio
- Roadworthy all-metal chassis construction
- 9V DC supply or battery capable (not included)