Mountable Indoor Wired Speakers - Traditional passive speaker design, simply powered from your amplifier or receiver. High Quality - Full range sound coverage with 2.5" polypropylene woofers, frequency response is 150Hz-20 kHz with 88dB at 8 Ohm. Durable and Mountable - Black ABS sealed cabinets with spring-loaded raw wire connectors and mounting brackets. Impressive sound from a compact speaker size of (H x W x D) 3.5" x 3.5" x 4.5" each. System Requirements - Any amplifier or receiver with raw speaker wire outputs, power from your amp should be at least 20 and not exceed 200 watts per channel, CL3 or raw speaker wire to connect your amp to the speakers