The Ferrofish B4000+ is a digital organ expander module that simulates all 91 tonewheels, with optional crosstalk and mechanical wear. It provides nine drawbars and three fully polyphonic manuals for Upper, Lower and Pedal parts, playable simultaneously. Integrated processing includes rotor, chorus, amplifier simulation, vibrato and reverb. The module includes a TFT color display, presets, USB MIDI, two MIDI inputs, audio and headphone outputs, and inputs for swell and rotor pedals.