Specification: Speaker – 100 mm (4 inch.) Cone Rated Power – 21 W Impedance – 4 ohm Sensitivity – 90 dB / W at 1 m Frequency Response – 45 Hz ~ 20,000 Hz Cutout Diameter – 10.2 cm (4 inch) Circle Mounting Depth – 4.3 cm (1-11/16 in.) Peak Power – 210 W