The speakers are rated to 8 Ohms. If you run two pairs of these speakers (4 speakers), the impedance will drop to 4 Ohms. Please make sure that your amplifier is 4 Ohm compatible before setting up 4 speakers. Housed in a rugged ABS plastic casing with a subtle, yet durable mesh grille, these speakers will look stylish & discrete in most environments. Each enclosure contains a high quality 1 Inch polymer tweeter and a 5.25 Inch surround woofer to produce a professional quality sound.There is an adjustable mounting bracket on the back of each speaker allowing you to securely position each speaker where it needs to be. 2-Way Speakers Speaker Cable Binding Post Connections (suitable for 4mm banana plugs) Max Power 8Ohm - 90w Power RMS 8Ohm - 45w Sensitivity (1m, 1W) - 88DB Frequency Response - 110Hz-20kHz Impedance - 8 ohms. We also stock a great range of stereo amplifiers and speaker cable allowing you to create a brilliant and low cost surround sound or PA system easily.