Here's what Mission Engineering say about the Expression Pedal:
Co-designed by Mission and RJM, the SP1-RJM is an optimized version of the SP-1 switching expression pedal for the Mastermind GT and Mastermind PBC MIDI Controllers
Expression and switch outputs on the pedal connect to inputs on the rear panel of the Mastermind. The expression pedals can be used to control external MIDI effects such wah, whammy and volume.
The integrated toe switch can be used to turn effects on and off, or toggle between effects. An LED on the front of the pedal is signaled to by the Mastermind and can be used to indicate state. For example, you can tell if your wah is turned on and the expression pedal assigned to it. One pedal can be connected to the Mastermind PBC and up to four pedals can be simultaneously connected to each Mastermind GT.
- Pedal dimensions are 10″ x 4″ x 3″
- Weight is 3.2lb
- Potentiometer is 10K Ohm Linear
- Switch is momentary