The FU SUPER TWEETERS 4.0" is an extremely efficient high frequency transducer, capable of adding brilliance and articulation to any sound reinforcement system. A virtually indestructible phenolic diaphragm bonded to a polyimide voice coil former contributes to the ring radiator driver's durability and non-fatiguing sound quality. Bullet type speakers provide clear imaging of audio program material over a wide range of frequencies and dynamic ranges, a high-temperature ferrofluid cooled voice coil and included crossover capacitor. Provides great results when deployed individually or arrayed in multiples.