JBL ES10BK 3-Way, 4" Bookshelf Speaker - Black (Pair) Frequency Response: 65Hz-40kHz Nominal Impedance: 8 Ohms High-Frequency Transducer: 19mm (3/4-Inch) Titanium- laminate dome, shielded, EOS waveguide, Ultrahigh-Frequency Transducer: 19mm (3/4-Inch) Polyester film, ring radiator, shielded, EOS waveguide Low-Frequency Transducer: 100mm (4-Inch) PolyPlas, shielded Maximum recommended amplifier power is 100 watts.