Blast your favorite music on the open water with the Boss Audio Indoor/Outdoor 3-Way Speakers. These 4" speakers operate at a maximum of 200 watts and are perfect for marine vessel applications.Midrange Poly InjectionPolyurethane, categorized as a polymer, is a resilient, flexible, and durable manufactured material that can take the place of paint, cotton, rubber, metal, or wood in thousands of applications across virtually all fields. It can be hard like fiberglass, squishy like upholstery foam, protective like varnish, bouncy like rubber, or sticky like glue. In the specific case of our cones, this material allows for maximum flexibility that produces great sounding speakers lasting you a long time.Surround RubberRubber is a synthetic (man made) material and is valued for its chemical inertness, impermeability to air, and the ability to endure or resist exposure to the many types of weather fronts. Rubber has applications from sports equipment to automotive parts, the medical industry and more. We use them for the surrounds that connect the cone to the basket. Did you know that most modern chewing gum uses food-grade rubber as the central gum base, which contributes not only the gum's elasticity but an obstinate, sticky quality? Just like that chewing gum, the rubber surround in our speakers can take the equivalent amount of abuse without quitting on you.Voice Coil AluminumOne of the most abundant elements on earth, aluminum is remarkable for its low density and for its ability to resist corrosion. It is nonmagnetic (does not have any magnetic properties) and does not easily ignite. This solid material has the ability to perform under stress in both high tension and high compression environments.Aluminum is relatively soft, making it one of the more ideal materials to use in voice coils.