Free Air REVO subs are recommended primarily for Infinite Baffle (Free Air) applications where a dedicated subwoofer enclosure is not available or practical. Both 10 & 12 REVO FA subs are available in White or Black frames (Black frames use metallic grey cones). All REVO FA Subs are available in either single 2 Ohm or single 4 Ohm impedances. All REVO 10 & 12 Subwoofers share the same design features: Nylas Composite Frame - to withstand extreme environmental use. Designed to accept optional RGB wiring. Injection Molded Composite Cone For durability & low distortion. Santoprene Rubber Spider Much more durable to water & temperature changes than a traditional treated Cotton Spider used by the majority of marine speakers & subwoofers. Santoprene Rubber Surround Offers a superior bond to the composite cone. Stainless Steel Terminals