The SVT410HLF is a speaker that can be used as a single speaker safely, without renouncing the desired pressure. It is larger than the conventional 4x 10 speakers, and was equipped with three reflex ports. The total impedance is 4O and therefore fits perfectly to most amplifiers. Amazingly is the rich and deep bass, which is reproduced by the relatively small box. This subwoofer produces an enormous amount of pressure!