USB Features: Support MP4. Built in 450W power amplifier. Power supply: DC 12V. Radio Frequency :US AND EUR. Meets ASTM B117 salt/fog standard. Speaker Size: 6.5. 1/2 PEI diaphragm tweeter. Shell size: 180 mm (7). Mounting Depth: 57.6 mm (2.26). Mounting Hole Diameter: 129 mm (5). Frequency Response: 120Hz – 20kHz. Voice Coil Impedance:4? Voice Coil Size:25mm. Voice Coil Material: ASV. Cone/Edge: PP cone/Rubber Edge. Resonant Freq(FO):85HZ + 20%Hz. Freq Response:85Hz-12 KHz. Marine Rubber Radio Antenna. Waterproof and resists corrosion. Perfect for boats and campers. 13.3inch Long Mast. 1 pcs Marine Radio. 1 pair Marine Speaker. All items will be tested in advance before sending out. Gushi, our company is dedicating to reseach & development of marine audio series products. If you are dissatisfied for any reason, please donot be quick to leave negative/neutral feedback. Our working time:Monday to Friday.