The plug fits inside the device, and the connector is the port it attaches to. Here's what you need to know about the physical compatibility of micro USBs: Micro-A plug: Micro-AB USB 2.0 and 3.0 receptacles. Micro-B plug: Micro-B USB 2.0 and 3.0 receptacles & Micro-AB USB 2.0 and 3.0 receptacles.