POWER ACOUSTIK D1-4000D Demon 4000 Watt Mono Bass Amp MOSFET PWM Power Supply: Metal Oxide Semi-conductor Field Effect Transistors with Pulse Width Modulated circuitry make up each DEMON amplifiers power supply. MOSFET transistors increase durability and longevity over bi-polar counterparts. Variable 12dB Crossovers: Filter out frequencies that could cause damage to speakers, or that subwoofers can't play via 12dB/octave slope high pass, low pass and subsonic crossovers. Dash Mount Remote Gain Control: Mono Bass DEMON amplifiers include a dash mount remote gain control. The remote gain control allows amplifier level adjustment from a remote location in the vehicle. Variable 18dB Bass Boost: All DEMON series amplifiers feature an 18dB 45Hz parametric bass boost. Mono Bass models offer variable boost level adjustment to match the limitations of your subwoofers. 1-Ohm Stable Class D, w/ 200mV-6V Low Level Inputs & High Level Inputs, 180 degree Phase Switch, Three-Way Protection Circuitry, Pre-Amp Outputs, 4 ga. Power & 8 ga. Speaker Terminals, Extruded Aluminum Brushed Finish w/ Red Anodizing