Planet Audio PCBLK3.5 &ndash; 3.5 Farad Car Capacitor For Energy Storage To Enhance Bass Demand From Audio System 3 Digit Bright Red Digital LED Voltage Display Audible Warning Tone for Reverse Polarity, Voltage Overload and Low Battery Voltage Capacitance: 3,500,000, Capacitance Tolerance: + / - 10%, Voltage Measurement Accurate to + / - 0.1 VDC Working Voltage: 20 VDC, Equivalent Series Resistance: &lt;0.00195 mW @ 120 Hz / 25C Dimensions: 4 x 4 x 11.4, Unit Weight: 6.4 Lbs 1 Year Warranty