Fountek NeoCD3.0 3" Ribbon Tweeter Super strong Neodymium magnets Build-in impedance conversion transformer Effective from 1,400Hz upwards due to the large diaphragm area and low self-resonance. Thin enforced sandwich ribbon diaphragm guarantees a high degree of signal fidelity and broad frequency response. Low distortion factor, good power-handling capabilities, high linear impedance and amplitude frequency response and the broad frequency response range. Flat impedance from 1,000 to 40,000Hz Warning: Ribbon tweeters should always be used with a passive crossover! They are a dead short to the amplifier. Do not test without a capacitor. Do not use an electronic crossover without a capacitor. We recommend at least a 20mfd.