The CVToolbox (manufactured by KissBox) is an hardware control module for analog synthesizers. It provides eight CV (Control Voltage) channels with 16 bits resolution to control any kind of analog synthesizer (modular or desktop). Each output can be controlled by the internal synthesizer engine, or by the kissbox.cvtoolbox external.
The kissbox.cvtoolbox external allows to control any CVToolbox output in real-time from a Max/MSP patch. For example, you can put an ~adsr object on a patch and use it to control hardware modules like VCF, VCA, etc... like if the synthesizer is a part of the patch (or like Max/MSP is a part of your synthesizer).
The external is available both for Windows and Mac OS platforms and can be used under Max5 and Max6.