It's probably the fastest way of downloading SRA files from the Short Read Archive.
It's considerably faster than using fastq-dump in its download mode (note that fastq-dump will still be required to convert the SRA files into fastq.gz files.
It's a semi-commercial tool, owned by IBM, but via the NCBI website it's possible to get a free version.
Maybe due to its commercial nature, it can seemingly be only installed as a normal user. I.e. a system-wide installation is not possible.
Where to get it
- here (via NCBI's page).