Bluetooth Stereo Audio Receiver Marine Radio + 4 x Boat Speaker + Antenna. USB Features: Support MP3 Fits in Gauge Opening. Power supply: DC 12V. Radio Response Bandwidth:US AND EUR. Meets ASTM B117 salt/fog standard. Dimensions Mounting Hole: 78.5mm. Dimension Mounting Depth: 41mm. Mounting Hole Diameter: 97mm(3.818). Mounting Depth: 35mm/(1.37). Grill material: UV Plastic. Magnet Material: Ferrite, 4oz. Magnet Protection: Plastic Water Guard. Application: Boat, yacht, SPA, swimming pool, ATV, UTV. Waterproof Engineering Design For Humid Environment, Indoor/outdoor Available. Waterproof Grade IP66, Meets ASTM 117 salt/fog Standard. The Flexible Mast Helps it Withstand Bracing Winds. Antenna Length: 13.3. 4 Inch Marine Waterproof Speakers. All items will be tested in advance before sending out. We will offer replacement without extra charger after we receive the defective item. Due to the recent lack of logistics transportation capacityOnly for orders ordered from Friday evening to Sunday, and logistics and transportation are normal from Monday to Thursday. GUZARE marine series of head units and remotes are fully tested against UV radiation degradation as well as tested to IP66 water intrusion standards. We also fully test the stereo units for every changing environmental conditions that you may experience on the boat or out in the dunes such as temperature extremes, as well as vibration testing to make sure they can take a bump and keep performing as a high standard product. If you are dissatisfied for any reason, please do not be quick to leave negative/neutral feedback. Our working time: Monday to Friday.