This is an Electro-Harmonix EU 7.5 AC 400mA power supply.
Every musician battles hum in their signal chain. The Hum Debugger turns it into dead silence, courtesy of a little EHX magic. Not a noise gate, and not a noise suppressor -- but a real hum extractor. Silence is golden. This is a great spare power unit for your Electro Harmonix Hum Debugger pedal