Efficiency: 90

20 cm (8 inch) subwoofer250/500 Watt RMS/MAX

Force factor (BL): 15

Designed for maximum control and enormous power reserves

fully symmetrical design and high-quality materials

PBR400X4D ESX Efficiency: 90Rockford Fosgate Punch PBR Amplifier Rockford Fosgate PUNCH PBR amplifiers with boosted rail technology break new ground in efficient amplifier design and ensure very high efficiency and low distortion. If you have limited space in your vehicle, these amplifiers are perfect for you. They also feature a variable high level DC offset circuit for easy installation into any OEM system. These amps are great for smaller stealth installations, motorcycles