Hertz UNO S 300 S4 12" 30cm Car Audio Sub Component Subwoofer 4 Ohm 250w RMSHERTZ S 300 S4 Subwoofer300 (12) mm (in.) Uno subwoofer 1000 W 4 Ohm The 30 cm (12) S 300 S4 car audio subwoofer, designed to obtain powerful deep bass in any installation, is the last addition to the Uno product range. Thanks to the efficiency of 89. 5 dB, achieved using lightweight materials such as paper for the cone and high density foam for the suspension, the component provides the ability to easily reach high sound pressures in the car