The Carl Martin Combinator 2 is a non-MIDI programmable effects switching system that handles up to eight pedals. Each pedal is connected to one of eight individual effects loops (two with stereo returns), and then assigned to one or more of 18 groups. Pushing the program switch for a group simultaneously engages all of the pedals assigned to it. So, for example, if you have a fuzz, a wah, and a chorus assigned to program switch 1, pressing that switch will turn them all on or off.  The Combinator 2 features 18 programs, tuner output, master mute, and external switching on loops 1, 2, and 3, each with a separate jack.