I have an old Samsung tablet with a USB micro 3, gathering dust in a drawer somewhere. Galaxy tab 2 or 3 maybe? It was a top-of-the-line device in that era, and the only device I've ever seen with that funky connector. I actually find it curious we didn't see the standard more, as it's backwards-compatible with regular micro-USB in a pinch, but when you did use the proper cable it enabled both faster charging and data transfer.