Hertz St 25 Set Ndym Bullet Compression Tweeter 25 Mm Size: 25mm / 1" Power Handling: 100W RMS / 200W Peak Impedance: 4-Ohm Frequency response: 3k  20k Hz | Sensitivity: 107dB SPL | Voice coil: 25mm / 1" Magnet: Neodymium | Cone/Dome: Aluminium