ISO 3166-2 geocode for Argentina. This is used as an international standard for shipping to Argentina. Each Argentinian province has its own code with the prefix AR.. For example, the code for the Province of Buenos Aires is ISO 3166-2:AR-B.
The USB 2.0 interface can be a limit due to signalling and command overhead as well as spacing between packets. I have a fast SSD connected by USB 2.0. The drive is much faster than the interface (by more a factor of 10). Read Speed maxes out around 33 MB/s and Write Speed at 17.5 MB/s. Write Speeds are almost 50% slower due to a verify-read after the write and the fact that the USB signal is half-duplex as another answer mentions.
A class 10 is the fastet of the old speed class ratings and a class 10 card is verified to never write slower than 10 MB/s, class 4 would be never slower than 4 MB/s. UHS Rating The UHS rating of a card determines the maximum bus speed at which a card can read, assuming the memory in the card is fast enough to match it. Non-UHS cards max out at 25 MB/s, while UHS-I cards support up to 104 MB/s, and UHS-II cards support up to 312 MB/s.