Midi thing is a small battery-powered box that connects between the midi-out of a keyboard controller to the midi-in of a sound generating module, or other device such as an iPad or iPhone.
It has just one switch and this is for turning the power on and off. Control of the looper is achieved by activating a “command” mode.
This mode suspends the notes on your keyboard and turns them into command controls.
You can find out more by taking a look at the instructions page.