via guyd2.com
"The Model 416 Meta Expander is a fully-fledged, standalone breakout-box for the BEMI Music Easel, which provides access to all of the Easel- and Program Card's patch points (effectively doubling the Easel's control voltage possibilities), and greatly extends the Easel's capabilities by having several useful modules build in.

A quick rundown of the Model 416 Meta Expander's capabilities:

Bringing out extra patch points not accessible on the Easel's patch panel. Full control over the Envelope's Attack, Sustain & Release. Voltage control over the Complex Osc's Waveshape Level. Access to all of the Sequencer's steps, and control over its number of Stages. Access to Random Voltages 3 & 4 (the Easel's patch panel only provides RV's 1 & 2).
Trigger inputs for the Sequencer, Envelope, Pulser & Random, opening up the Easel to external synchronisation.
Full voltage control over most of the Easel's switches.
In addition, the Model 416 Meta Expander offers extra custom-designed modules to vastly expand upon the Easel's features:
Two fast Comparators, with threshold control, for pulse generation, with both 3.5mm & banana inputs, separate outputs (2ms @ 10V), as well as a combined output (A+B). They can drive any triggerable module in the Easel.
A Noise module with White, Pink-ish and Slow-Varying Random outputs. Since White & Pink Noise are simultaneously available at Tini-jax & banana outputs, they can serve as both modulation- and audio sources. Slow Random is available at several patch points across the panel.