These Secure Digital, microSD, CompactFlash, XQD and CFast card reader reviews include read and write speed tests using several memory cards. Most readers support USB 3.0 or USB 3.1 for maximum transfer speed. USB 3.0 is capable of up to 500 MB/s speed. USB 3.1 is capable of up to 5 or 10 GB/s. If you have a computer with only USB 2.0, USB 3.0 card readers are backwards compatible but limited to 35MB/s which is the maximum speed possible with USB 2.0. In most desktop computers it is possible to upgrade to USB 3.0 by adding a PCI-e USB 3.0 expansion card such as the Silverstone Tek EC04-P.
The most common type of USB port is the standard USB Type-A. A newer standard USB Type-C (or USB-C) is finding its way onto laptops and other devices. This port requires a special connector. Few USB card readers are available with USB-C connectors, but more are on the way.