Boss Audio Systems R63 300 Watt Per Pair, 6.5 Inch, Full Range, 3 Way Car Speakers Sold in Pairs

A substance called “Polyurethane” and is categorized as a “Polymer". It 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, long time.