Computer algorithms are different from U disk capacity algorithms. Computer algorithm is 1GB = 1024MB, however, U disk capacity algorithm is 1GB = 1000MB.
Therefore, the actual amount of memory is slightly less, i.e. 4GB (3.65GB to 3.8GB), 8GB (7.40GB to 7.55GB), 16GB (14.8GB to 15.1GB), 32GB (29.2GB to 31GB).
Read and write speed :3-6m / s, read speed: 18m / s (transmission speed over a certain relationship with the use of computer configuration.)