This is a device used for keeping fish alive while fishing, by bubbling air into the water. I used to raise killifish in an outdoor hibachi, and occasionally used this during the summer. I mainly used a solar-powered bubbler, but it would sometimes stop working when it rained, so I used this as an emergency backup. I've confirmed that it works before listing it. It takes two size-D batteries, but for some reason, it works with just one. I don't quite remember, but I think two full batteries only lasted about a day. It might have been only two or three hours. I remember thinking that the batteries cost more than I expected. I saw one at a nearby store for 2,800 yen! I think you'd be better off getting one from Daiso, since they have them. Shipping: Rakuraku Mercari Delivery, Takkyubin Compact, to be shipped in a dedicated box.