Just like their bigger brother the 520, the Alesis M1A 320 USB are a pair of active studio monitors which will connect to your computer directly over USB. Sporting compact 3" drive units and a rear ported bass reflex the 320s manage to rattle out an impressive amount of bass for such a small monitor speaker. They also work as an audio interface for your computer so, you can record the output of you DJ mixer, drum machine or similar. They manage to do all of this without drivers for instant plug and play setup.
If you need a pair of speakers that are transportable or, indeed, if you're struggling for space with your studio or DJ setup then the Alesis M1A 320 USB might be just what you've been looking for.