Custom Terminal Block for Speaker Connection Thermal / Overload / Short Circuit Protection.Input Impedance: 47K Ohms Soft Turn On/ Off Advanced Protection Circuitry S/N Ratio: >90dB Dimensions:10.24''W x 2.21''H x 17.72''L When power isn’t enough, you need Pyle Power. This four-channel, 4000-watt power supply is bridgeable. It’s equipped with everything you’ve come to expect from quality car amplifiers. The RCA ports are silver-plated for eliminating signal loss. A subsonic filter allows low-end interference to be cut, so your speakers will always be delivered the highest quality audio. The MOSFET pulse width modulation power supply allows for a clean, distortion-free signal to your speakers. To keep both your car and the amplifier safe, this model is equipped with thermal, overload, and short circuit protection. So when what you need is power, trust Pyle Power.