Boss Guitar Effects Guide Book Vol 7 (1991):

Five ideal effects for bass guitar in one compact unit Limiter, overdrive, enhancer, graphic equalizer and digital delay/ chorus/flanger are included. All circuitry is designed especially for bass guitar.

The Enhancer brings out the clarity and “presence” of bass guitar sounds, even sounds in the lower frequency ranges.

BE-5B Bass Multiple Effects

The graphic equalizer features 10 bands accommodating the frequency range of a bass guitar
The overdrive is designed with a speaker simulation circuit so that thick, amp-like sounds are obtained even when the BE-5B is connected directly to a mixer.
Send and return jacks are provided for the connection of external effect units, as well as a tuner out for speedy tuning.