View larger Specifications 5 x 7 inch, 250 watt 2-way speakersImpedance: 4 OhmsFrequency: 100Hz – 18KHzSensitivity: 90 dB @ 1 W/1 mMounting depth: 2-1/16” (53mm)What Comes In The Box? One pair of speaker wiresMounting screwsTwo custom tooled grillesMounting template View larger Cone – Poly Injection Polyurethane, 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 upholstery foam that can be protective like varnish, bouncy like rubber, or sticky like glue. In the case of our cones, this material allows for maximum flexibility that produces great sounding speakers lasting a long time. View larger Tweeter – Dome Generally, the dome tweeter is a step up from the semi-dome tweeter, primarily because of improved sound dispersion. The dome shape radiates sound with a wider dispersion pattern than the semi-dome design. Since high-frequency sound waves are very directional, a wider dispersion of the sound waves will give you a larger "sweet spot" to work with when setting up your system. View larger Voice Coil – Aluminum Our speakers are capable of higher or elevated temperature strength and fatigue properties that will increase performance and efficiency of heavy duty play time through lower weight and higher operating temperatures. View larger Rear Of CER572 View larger Surround – Rubber Rubber 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 it for the surrounds that connect the cone to the basket. Just as chewing gum uses food-grade butyl rubber as the central gum base, which contributes not only the gum's elasticity but an obstinate, sticky quality, the butyl rubber surround in our speakers can take the equivalent amount of abuse without quitting.