Revolutionary! No word better describes the patent-pending Boston Acoustics SPG555 reference subwoofer! It uses a powerful neodymium structure that reduces it's weight to approximately half of other designs yet works within enclosure volumes as small as 1-cubic foot! Add in features such as our unique RVC & SPS replaceable systems, compact size, minimal weight construction, powerful yet accurate output, and you have a reference subwoofer unlike any other. In other words, what you have come to expect from all Boston Acoustics car audio products regardless of price.