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.
Only 32GB is available; even less when you factor in the OS and recovery partitions already installed. eMMC flash memory is nearly impervious to shock and vibration. eMMC is cheaper than it's SSD brethren and the larger spindle drives. A typical specimen will read 250MB/sec and write 90MB/sec (vs 130MB/sec read and 100MB/sec write for spindles).