New in box. From the manufacturer: The Micro Amp allows you to boost your signal with a preset amount of gain up to +26dB. This pedal can be powered by a 9-volt battery, a Dunlop ECB003 9-volt adapter, or the DC Brick™, Iso-Brick™, and Mini Iso-Brick™ power supplies (not included).
Adding a preset amount of gain with just a single control, the Micro Amp is a great way to boost your signal for lead work or adjust between two different guitars with unmatched output (i.e. humbuckers to single-coils). It can also provide a permanent boost in a long effects chain where signal drop off is a problem.