A product research booklet on the ONKYO SL-1 - a passive radiator active subwoofer with a 38 cm woofer and built-in amplifier. The format is unusual: the bulk of the booklet is a dialogue between audio critic Hirasawa and reviewer Egawa about why a dedicated subwoofer makes sense in a home system and how to handle ultra-low frequency reproduction properly. The later pages cover technical specs with frequency response graphs and a breakdown of the passive radiator enclosure design.