Hifonics ZRX111A active spare wheel subwoofer. 28 cm (11) subwoofer 300 watts. 28 cm (11) subwoofer. 150 W RMS / 300 W max. Voice coil 76 mm on aluminium support. Subsonic filter 20 Hz fix. Phase switch 0 ° / 180 °. Bass boost 0-18 dB. Auto turn-on via high level inputs. Ø 36 H: 14.5 cm. With the Zeus series, Hifonics offers 2 spare wheel subwoofer solutions. A passive and an active version. These ZRX subwoofer systems. Fit in various spare wheels from 15 inches of different vehicle models.