The Selenium by JBL ST400 is a super tweeter for outstanding detail and clarity in high-frequencies without harshness. The ST400 may be used individually in lower power systems or arrayed for increased coverage and SPL in higher power systems and is equipped with quick coupling connectors. The base and diffuser are constructed of aluminum which contributes to better heat dissipation. The bullet-shape horn design offers a longer throw 40 x 40 degree dispersion. The phenolic annular diaphragm is long-lasting, cost effective and more natural-sounding than metallic diaphragms. The use of high-temperature materials and adhesives improves power handling and produces exceptionally high acoustic output. A precisely engineered diaphragm structure and alignment mechanism for easy, reliable, cost effective repair in case of diaphragm failure. SPECIFICATIONS: Power Handling: 150 watts RMS/300 watts max RMS Power Using Crossover (Active/Passive): NBR 10.303 (HPF 5.000 Hz 12 dB/oit): 100W / NBR 10.303 (HPF 8.000 Hz 12 dB/oit): 150W Music Program Power Using Crossover (Active/Passive): (HPF 5.000 Hz 12 dB/oit): 200W / (HPF 8.000 Hz 12 dB/oit): 300W Nominal Impedance: 8 ohms Voice Coil Diameter: 42mm Frequency Response: 4,000-20,000 Hz SPL: 111 dB 2.83V/1m DC Resistance: 6.2 ohms Voice Coil Winding Length: 2.2 meters Voice Coil Winding Depth: 2.0mm Sound Dispersion (H x V): 40 x 40 degrees Diaphragm Material: Phenolic Flux Density: 1.7 T Volume Displaced by Tweeter: 0.6 I Magnet Weight: 470g Net Weight: 1690g Connectors: Quick Coupling Front Baffle Cutout Diameter: 106mm Depth: 87mm Magnet Diameter: 102mm Magnet Height: 14mm