These satellites use Gallo Acoustics' proprietary 'S2' technology, which extends low frequency response a full two octaves lower than otherwise possible. The Micro satellite speakers are only 4 inches in diameter, but combined with a subwoofer, behave as though they were as large as bookshelf systems many times their size. They never sound thin, as do other satellite systems their size. The enclosures are steel. The spherical shape compresses the back wave of the driver to a point source. This maintains phase integrity. Eliminating crossovers allows a soundstage depth and resolution impossible for conventional speakers, no matter how expensive or large they might be.