I think I bought this from Sanwa Supply for around 2,000 yen a while ago. I bought it to use for switching apps, but I couldn't use it as intended when I was out and about, so I ended up putting it away. That's why I'm selling it now. You can find various pages if you search for "USB foot switch," so please refer to them for how to use it. It will be shipped via Nekopos.