Here's what Blackstar say
The FS-12 is a multi-function footcontroller in a compact, low profile, durable aluminium body that allows access to all 36 patches of the ID:CORE 100 / ID:CORE 150.
The large, clear dot matrix display ensures easy visibility for the fully chromatic tuner and current patch details.
Two user-configurable function switches provide control for:
- Modulation, Delay and Reverb effects on/off
- Modulation and Delay tap tempo
- Full Looper functionality
- Effects Loop on/off
- Super Widestereo on/off
- Noise Gate on/off
The FS-12 includes an extension socket for connection to the FS-13 2-button footcontroller (included with ID:CORE 100 / ID:CORE 150) In this configuration you can add two extra, programmable switches which are configurable via the Blackstar INSIDER software.