Thank you for viewing. For music production, video works, and podcasting. A high-quality 4-track audio recorder. Used indoors for about a month after purchasing new, and then stored. However, the surface of the main unit had undergone hydrolysis. I cleaned it with alcohol and a cloth, but it couldn't be completely removed, so I'm selling it as a "defective" item. ・Main unit only. ・Operation confirmed with AA batteries. ・Main unit microphone, external microphone inputs 1 and 2 all work normally. - Model name: H4n Pro