The SRA Toolkit and SDK from NCBI is a collection of tools and
libraries for using data in the INSDC (International Nucleotide
Sequence Database Collaboration) SRA (Sequence Read Archives).  The
SRA house sequence reads and alignments generated by DNA/RNA
sequencers.  The SRA Toolkit facilitates downloading sequence data,
performing filtering and conversions on-the-fly, thus saving enormous
amounts of time, bandwidth, and storage.