Audio Unlimited 900MHz Wireless Add-on Speaker (Black) (SPK-VELO2) Auto tuning function for interference free reception utilizing Phase Loop Lock (PLL) technologyautomatically tuning in the optimal frequency. 900 MHz transmitter sends audio signals without speaker wire (transmitter not included) Speaker can be up to 150' away from the audio source, without line of sight limitations Existing systems transmitter connects via 3.5mm audio cable to PCs, MP3 players, iPods, stereos and home theatre systems Compact & portable with a stylized design (10H x 5W) - 3 Rubber edge Woofer2 Mylar cone Tweeter 10 Watt RMS Output 9V DC Transformer